Greater Settlement Research Articles

Small-scale physical modelling of vertically loaded, cyclically thermally-activated helical piles

To investigate the use of thermally-activated helical piles in shallow geothermal energy systems, a 1-g modelling study was conducted. Helical piles with either a single- or double- helix were installed in a medium dense, dry sand, and subjected to mechanical, thermal only and thermo-mechanical loading. The results indicate that during the thermal tests (1 – 3 cycles), a small upwards residual displacement was observed and pile head movements ranged between about 90% and 100% of the free expansion of the pile shaft above the shallowest helix, suggesting that the helices fixed the shaft and little restraint was offered by the surrounding soil. In the thermo-mechanical tests (30 thermal cycles), the pile head developed irrecoverable settlement as a function of the number of helices (more helices, less settlement) and initial load (higher load, greater settlement). No significant alteration in pile axial stiffness or resistance was found for piles with zero mechanical load that underwent only a few thermal cycles; however, an increase in stiffness and resistance, beyond that due to inherent variability in the test setup, was observed for piles with an initial load and following a large number of thermal cycles. The testing of thermally-activated helical piles in sand has confirmed that the response is similar to conventional piles and that thermal ratcheting effects can be managed by the application of suitable margins of safety in design and/or the use of multi-helix piles.

Model testing of dynamic response of loess to impact load from helicopter landing

ABSTRACT To investigate the dynamic behaviour of loess under the impact loads of two tyres attached to a helicopter’s landing gear, a loading device capable of simultaneously applying dual impact loads was designed. A series of physical model tests, varying in impact energy and water content of the loess samples, were conducted. The study explored the settlement pattern, vertical dynamic stress distribution, and the effects of impact energy and water content. Results revealed that settlement in the shallow layer exhibits a characteristic W-shape, while the vertical dynamic stress time curve displays a single peak pulse. Settlement and vertical dynamic stress increase with higher impact energy. Increasing the water content of the loess sample results in greater settlement but lower vertical dynamic stress. For the simulated helicopter, when the tyre impact energy increases from 23.8 to 60.8 kJ, the resultant crater depth in loess with a moisture content of 16% increases from 7.6 to 18.1 cm, an increase of 11.5 cm. The peak vertical dynamic stress at a depth of 10 cm along the centerline of the tamper increases from 590.98 to 1449.4 kPa, more than doubling. These findings are valuable for the design of landing sites and landing gear systems.

Feasibility Study of Locally Excavated Soil in Foamed Cement Mixture as Backfill Material for Abutments of Railway Bridges

Abstract The varying stiffness of materials surrounding a railway bridge abutment section has caused concern for rapid deterioration. Particularly on the transition toward the bridge approach, a significant contributing factor to the bad experience is the consolidation of the backfill material used. The objective of this study is to conduct experimental research utilizing locally available soil in a lightweight foamed concrete mixture as an alternative sustainable solution. The new technique combines the merits of the self-leveling air foam and the early strength attainment of portland cement concatenate into a flowable soil mixture. To attain this objective, the properties of the flowable soil mixture are tested by using various laboratory experiments. Furthermore, a numerical simulation was utilized to evaluate the performance of the backfill material under cyclic train loads compared with the conventional cement-treated base. The test results suggested that air foam content noticeably improves the self-leveling of backfill material, however, it should be controlled at lower than 20 % to ensure sufficient strength gain. Adding more cement content and lowering the usage of air foam not only shortens the setting time to less than 12 h and enhances the compressive strength up to 1.45 MPa, but it also reinforces the frost resistance of the lightweight foamed soil mixture. In addition to the numerical simulation, the test results reveal that the new material provides great settlement resistance and can withstand vibration load for a railway track system. The elastic displacement can be reduced up to 21 % (2 mm), and the plastic settlement can be lower to more than 60 % (6 mm) under 10,000 cyclic loads. In general, the application of lightweight foamed soil mixture as a backfill material for railway bridge approach poses a green and sustainable alternative solution.

Improved Performance of Raft Foundation Using Detached Pile Columns in Loose Subsoil Conditions

Piles act as settlement reducers in case of connected piled‐raft foundation and hence decrease the settlements of the raft. The design concept of the connected piled‐raft foundations is to lessen the number of piles and utilize the bearing capacity of the system piled raft. Due to significant straining actions at the pile head‐raft connection, an alternative technique is proposed to disconnect the piles from the raft. A granular layer (cushion) beneath the raft is incorporated. The disconnection has a beneficial effect on reducing axial load compared to connected piles. For small piled rafts, nonconnected piled rafts show less stiffness than connected piled rafts, and the soil is highly stressed and shows greater raft settlement. In the case of the large piled raft, nonconnected piled rafts show greater settlement efficiency. Cushion stiffness was realized to be more substantial for a nonconnected piled raft with shorter piles than one with longer piles. The results show that the load transfer mechanism in a nonconnected piled raft is mainly governed by the thickness and stiffness of the cushion layer and by the stiffness of the subsoil.

Structures and Settlement Control of Yujingshan High-Speed Railway Tunnel Crossing Massive Rockfill in a Giant Karst Cave

The Yujingshan high-speed railway tunnel crosses a giant cavern system with a 108 × 104 m3 volume chamber and an 18 km long underground river. The massive project, which lasted three years, was eventually awarded the “Overcoming the Challenges” award by the International Tunneling and Underground Space Association (ITA) in 2020. However, since the cave chamber was filled with large-scale rockfill, structural settlement is a non-negligible problem. This paper presents the unique structures of a bridge supporting railway tracks wrapped by tunnel lining and the settlement control of the Yujingshan tunnel crossing massive rockfill in the giant cave. The geological characteristics and design considerations are systematically introduced. A three-dimensional coupling discrete element method (DEM) and finite difference method (FDM) numerical model and 13 months of long-term settlement monitoring were conducted to evaluate the settlement behavior. The results indicate that the morphology of cavern and internal deposits caused the whole rockfill to migrate to the lower left. The tunnel structure consequently developed a significant inclined settlement. The continuous construction load would increase the settlement value by 31.4%. The bottom reinforcement of steel-pipe pile with grouting could effectively inhibit settlement and differential settlement. Considering the simulation results, the tunnel bottom had greater settlement than the limit standard for high-speed railway embankment, which means this special structure form is reasonable for operation. Meanwhile, the monitoring results show that the tunnel bottom settlement in D3K279+891~D3K279+947 had not performed an apparent convergence trend after 13 months. Further structural monitoring and compensation grouting should be actively considered for operation maintenance.

Study on Mechanical and Tribological Characteristics of Epoxy Composites Reinforced with Short Areca-catechu Fibers

ABSTRACT This paper reports on the dry-sliding wear behavior of natural fiber fortified polymer composites. Such composites are fabricated using epoxy as the matrix and short areca-catechu fibers as the reinforcing element through the conventional hand lay-up route. Four different fiber loadings (0, 2, 4, 6 wt.%) are considered to get samples of different compositions. Physical and mechanical characteristics like density, porosity, and tensile strength are measured. Digimat-FE software is also used to determine the density and stress distribution of the composites. It is found that the tensile strength of composite increases about 47% compared to neat epoxy resin when with the addition of 6 wt.% fiber content. Dry sliding wear tests are carried out using a pin-on-disc test rig according to ASTM standards. Different sliding velocities, sliding distances, and normal loads are considered. Tests are designed as per Taguchi’s L16 orthogonal array and a specific wear rate for each test run is obtained. Noticeable control factors influencing the wear rate are pointed out and ranked. It is found that the reinforcement of short areca-catechu fibers helps in improving the wear resistance of epoxy in dry sliding wear mode. An optimum factor condition for the lowest wear rate is determined. Based on the data obtained from experiments, a predictive equation is proposed to find the specific wear rate of such composites under varied test conditions. The outcomes predicted by this proposed correlation are found to be in a great settlement with the experimental ones.

The living Corpus. New design developments of historical Alpine architecture

T”The Corpus of historical architecture – built by traditional societies in the Alps be-tween the great settlement phase of the twelfth-thirteenth century and the break caused by twentieth-century modernization – represents one of the main references when addressing the topic of building in the mountains. It is recognized as having authority. It is to it that we appeal – from the nineteenth-century Swiss-German treatises, through Adolf Loos and Giuseppe Pagano, to contemporary designers – to legitimize theories or to support collective images on building in the mountains. The Corpus of historical Alpine architecture, however, consists not only of the materiality of the buildings and infrastructures, but above all of the dense layering of exegesis and interpretations. The essay highlights how in recent years, however, it seems to be set in motion again through actions of a different nature: on the one hand, the weakening of a patrimonial paradigm that only placed the recognition of historical values and the conservation-enhancement of heritage at the center; on the other hand, the emergence of an unprecedented issue related to the construction of a new habitability in the Alps through projects for the revitalization and re-generation of territories based on the need for spaces that provide social interaction to the community, welfare, and culture production. This creates a new demand for the construction of “use values” that goes beyond the historical and symbolic values of heritage; thus, an unprecedented way of looking and thinking about things is required to prefigure a new civilization of the mountain in which legacies return to being a living body.”

Environmentally-induced parental or developmental conditioning influences coral offspring ecological performance

The persistence of reef building corals is threatened by human-induced environmental change. Maintaining coral reefs into the future requires not only the survival of adults, but also the influx of recruits to promote genetic diversity and retain cover following adult mortality. Few studies examine the linkages among multiple life stages of corals, despite a growing knowledge of carryover effects in other systems. We provide a novel test of coral parental conditioning to ocean acidification (OA) and tracking of offspring for 6 months post-release to better understand parental or developmental priming impacts on the processes of offspring recruitment and growth. Coral planulation was tracked for 3 months following adult exposure to high pCO2 and offspring from the second month were reciprocally exposed to ambient and high pCO2 for an additional 6 months. Offspring of parents exposed to high pCO2 had greater settlement and survivorship immediately following release, retained survivorship benefits during 1 and 6 months of continued exposure, and further displayed growth benefits to at least 1 month post release. Enhanced performance of offspring from parents exposed to high conditions was maintained despite the survivorship in both treatments declining in continued exposure to OA. Conditioning of the adults while they brood their larvae, or developmental acclimation of the larvae inside the adult polyps, may provide a form of hormetic conditioning, or environmental priming that elicits stimulatory effects. Defining mechanisms of positive acclimatization, with potential implications for carry over effects, cross-generational plasticity, and multi-generational plasticity, is critical to better understanding ecological and evolutionary dynamics of corals under regimes of increasing environmental disturbance. Considering environmentally-induced parental or developmental legacies in ecological and evolutionary projections may better account for coral reef response to the chronic stress regimes characteristic of climate change.

Recharging Ground Water Using Age– Old Traditional Mechanisms

“Give back unto the Earth if water is desired in the coming generations”“Pawan Guru, Pani Pita, Mata Dharat Mahat” the Gurbani or word of the Gurus as embodied in the holyGuru Granth Sahib has in these words immortalized the relationship of men with Nature by saying that the“Wind is the teacher; Water is Father while the entire Earth is the mother”. When this strong bonding of menand Nature had been recognized several centuries ago it stupefied the human senses to think that man hadended up destroying the natural habitat unmitigatedly.Since earliest times almost all natural resources have been reserved and utilized judiciously by civilizations.The Chinese, Indus valley, Mesopotamian, Roman, Aztec and most other great settlements used waterconservatively. Even back then there was concern for wastage of water.This paper is focused on looking at the systems of conserving, purifying water and utilizing it to the optimumwithout wasting any part of it. The objective of the paper is to determine the functioning and use of thesetechniques for present day communities.

ХРОНОЛОГИЯ II ТЫС. ДО Н. Э. И «ВЕЛИКИЙ ГОРОД ШАН (XIV–XI ВВ. ДО Н. Э.): КРАТКАЯ ХАРАКТЕРИСТИКА

Second half of the II millennium B.C. can be considered as the time when the first writing system appeared in East Asia in the form of oracle bone inscriptions jiagu wen (甲骨文). For the first time those inscriptions sparked academic interest and received recognition at the end of 19th century, though their place of origin remained a mystery for some time. At the end of the 1920s Archaeological department of Institute of History and Philology Academia Sinica initiated archaeological excavations near modern city of Anyang, Henan province, PRC, because it was implied that the oracle bones with inscriptions had originated there. Archaeological excavations reveled a great ancient center in Anyang, including a cult center, workshops, and cemeteries including royal necropolis. Due to the fact that names of rulers, known from the transmitted texts, were often mentioned in those inscriptions, it was possible to identify the site as the last capital of Shang-Yin dynasty, so-called ‘Great Settlement Shang’ (14th–11th centuries B.C.). All these make the complex rather unique for its time, as it gives us a chance to connect pre-historical and historical data. Researchers managed to determine two relative chronologies (based on archaeological and epigraphic sources) and later to interconnect them and relate to the events mentioned in transmitted texts on early political history. Still, there is a number of problems in correlating those relative chronologies with absolute dates. Up to now the greatest project to coordinate chronology of the II millennium B.C. has been the project “Chronology of the Three Dynasties: Xia–Shang–Zhou” in 1996–2000, initiated by the Chinese political figure Song Jiang. Regardless of some international criticism of the projects’ results, a great number of scholars make use of them in their studies.

Federal Forum Provisions: Historical Development and Future Evolution

The Securities Act of 1933 provides for concurrent federal and state jurisdiction. In 2015, plaintiffs significantly increased the frequency with which they filed Securities Act claims in state court, where dismissal rates are lower and weaker claims have greater settlement value. The cost of directors and officers insurance for issuers conducting initial public offerings, the form of transaction most sensitive to Securities Act litigation risk, has increased dramatically. This increase is concurrent with plaintiffs’ shift away from federal court. Federal Forum Provisions (FFPs) appear in charters or bylaws. They require that Securities Act claims be litigated in their traditional forum, federal court. FFPs arose as a direct response to plaintiffs’ shift from federal to state court Securities Act litigation. In Sciabacucchi, Delaware Chancery held that FFPs are invalid. That opinion is currently on appeal to Delaware’s Supreme Court. Part I of this note reviews data documenting the migration of Securities Act claims from federal to state court, and shows that approximately 75% of all issuers today facing Securities Act claims face at least one complaint filed in state court. Part II analyses plaintiffs’ incentive to migrate, and focuses on the lower probability of state court dismissal, combined with an array of other procedural advantages that benefit plaintiffs in state court. Part III presents novel data documenting a rapid and significant increase in the cost of directors’ and officers’ insurance. Part IV documents the evolution and propagation of FFPs, and shows that they have been adopted primarily by Delaware-chartered issuers who face a significant risk of Securities Act IPO litigation. Part V summarizes other scholars’ findings that the stock prices of issuers with FFPs declined in a statistically and financially significant manner in response to Chancery’s decision in Sciabacucchi. Part VI concludes with observations regarding the future evolution of FFPs contingent on the pending decision by Delaware’s Supreme Court. If FFPs are upheld as valid, then Delaware will have a further advantage in the market for corporate charters. If FFPs are held invalid, issuers will face incentives to petition other states to adopt legislation affirming the validity of FFPs. If that occurs, insurers will have a rational incentive to impose a “Delaware penalty” on issuers who are likely subject to Securities Act liability and who charter in Delaware rather than in states that enforce FFPs. If this market response emerges, it will be the first instance in which there is an immediate, quantifiable reason not to charter in Delaware. This result cannot be positive for Delaware’s ability to compete in the market for corporate charters.

Monitoring and characterizing the deformation of an earth dam in Guangxi Province, China

Failures and severe deformation of earth dams have been reported frequently in the past decades. Extensive studies have been performed to monitor dam displacements to develop dam remediation plans. However, the long-term monitoring of dam displacements and the effects of remediation on dam deformation are rarely studied. In this study, the vertical and lateral displacements of an earth dam in Guangxi Province, southwestern China, were monitored over an 18-year period. The piezometric pressure was measured for the analysis of triggered seepage. Furthermore, acoustic testing and borehole television tests were performed to examine the integrity of the cutoff wall that was built to prevent dam leakage and excessive deformation. The results show that the largest lateral displacement of 65.8 mm and the maximum settlement of 178 mm are both located at the center of the dam and that the lateral displacement and settlement decrease gradually from the center to both abutments. Moreover, greater settlements were observed on the side of the dam upstream of the cutoff wall. The lateral displacements are dominated by the hydraulic pressure of the impounded water. The dam settlements are generally determined by the thickness of the compacted soil along the longitudinal section. The analysis shows that the greater settlements on the upstream side of the dam are attributed to dynamic seepage induced by the water level changes in the reservoir, indicating that the cutoff wall effectively alleviated the seepage effects on the downstream side of the dam. Thus, the dam's upstream face should be remediated to minimize the dynamic water-level effects.

Dynamic characteristics research of a ground fissure site at Xi’an, China

This paper studies the seismic response of an active ground fissure site subjected to earthquake by the shaking table model test. The settlement was induced by the earthquake in the ground fissure site. The settlement increased with the earthquake peak acceleration. The differential settlement has a third-order polynomial relationship with the earthquake intensity. The process of the settlement has three periods, including the rapid deformation stage, the stable deformation stage, and the accelerated development stage. The greatest settlement is in the hanging wall close to the fissure. The secondary fissures and new cracks developed and appeared during the earthquake. The high frequency component of the wave was reduced from the bottom to the top of the site and the low frequency component was amplified. The Fourier amplitude gradual increases correspond to the earthquake acceleration. The results discovery the relationship of subsidence, widen of fissure and the earthquake. It is contribute to the metro design of the fissure area.

The Miguel map revisited

The Miguel map was drawn by a native of Kansas in 1602 at the behest of Spanish officials in Mexico City. The map shows native settlements, rivers, trails, and two salt marshes in the Southern Plains and a spot from which gold was obtained. Previous attempts to decipher the map have not used all of the ancillary documents and have depended on early translations with errors of both transcription and translation. Information from eyewitness accounts from the 1601 Oñate expedition show that the place called Etzanoa and the great settlement is located at Arkansas City, Kansas. The map also shows the location of other ancestral Wichita communities and camps of the nomadic Escanxaque. Finally, it shows a place labeled Encuche, where gold was smelted, the location of which turns out to be in South America.

Effects of frequency and cyclic stress ratio on creep behavior of clay under cyclic loading

ABSTRACTThe mechanical behavior of clay subjected to cyclic loading is important to consider in the design of the foundations of many types of structures that must resist cyclic loading, such as subgrades and offshore foundations, because clay undergoes greater settlement under cyclic loading than under static loading. The difference in settlement between these two loading patterns due to creep behavior is affected by the cyclic frequency and the cyclic stress ratio. This study investigated the effects of the frequency and cyclic stress ratio of cyclic loading on the creep behavior of a natural clay in China using stress-controlled triaxial tests. The assessed the following parameters: three frequencies, four cyclic stress ratios, and six vertical stresses. The test results indicate that the soft clay displays accelerated creep behavior under dynamic loads. A specific “limit frequency” (in this case, 0.2 Hz) and a “safe load” at which the strain of the soft clay increases very slowly were observed. The effect of the effective axial stress on the creep behavior increases with the increase in the cyclic stress ratio. Based on the tests, the critical cyclic stress ratio is 0.267 at a certain effective axial stress and frequency.

Complex offspring size effects: variations across life stages and between species.

Classical optimality models of offspring size and number assume a monotonically increasing relationship between offspring size and performance. In aquatic organisms with complex life cycles, the size–performance function is particularly hard to grasp because measures of performance are varied and their relationships with size may not be consistent throughout early ontogeny. Here, we examine size effects in premetamorphic (larval) and postmetamorphic (juvenile) stages of brooding marine animals and show that they vary contextually in strength and direction during ontogeny and among species. Larger offspring of the sea anemone Urticina felina generally outperformed small siblings at the larval stage (i.e., greater settlement and survival rates under suboptimal conditions). However, results differed when analyses were conducted at the intrabrood versus across-brood levels, suggesting that the relationship between larval size and performance is mediated by parentage. At the juvenile stage (15 months), small offspring were less susceptible than large ones to predation by subadult nudibranchs and both sizes performed similarly when facing adult nudibranchs. In a sympatric species with a different life history (Aulactinia stella), all juveniles suffered similar predation rates by subadult nudibranchs, but smaller juveniles performed better (lower mortalities) when facing adult nudibranchs. Size differences in premetamorphic performance of U. felina were linked to total lipid contents of larvae, whereas size-specific predation of juvenile stages followed the general predictions of the optimal foraging strategy. These findings emphasize the challenge in gathering empirical support for a positive monotonic size–performance function in taxa that exhibit complex life cycles, which are dominant in the sea.

Interaction between stocking density and settlement on population dynamics in suspended mussel culture

Population dynamics on mussels growing on suspended culture depend mainly on the balance of several processes: mortality and/or dislodgements from the ropes, recruitment and growth. The negative effect of overcrowding on mussel growth and survival has been widely studied. Other works have addressed the effect of population size on recruitment on bottom beds. This study aims to provide insight into the processes underlying population dynamics. To this purpose, we analyzed the effect of stocking density on mussel growth, survival and seed settlement, and the post-settlement interaction between adults and recruits in suspended culture. The temporal pattern of the variables involved in population dynamics was fitted by GAM models, which in contrast with parametric models does not assume any prior relationships between variables. Our results show that mussel growth and survival depend on a trade-off between competition for resources at high densities and the risk of great settlements in less crowded adult mussel populations. Intracohort competition increased with stocking density, while seed settlement, which increases the risk of mussel dislodgements and leads to intercohort competition, was higher at moderate stocking densities. Post-settlement competitive pressures were driven by total population density and size composition. Both intracohort competition in adults and asymmetric competition between adults and recruits increase with higher adult–recruit ratios. All these density-dependent processes should be considered in future management strategies and research experimental designs.

Vicente de Zaldívar in New Mexico: Edition and Notes to Part 3 of the Probanza de méritos (1602)

Vicente de Zaldívar in New Mexico: Edition and Notes to Part 3 of the Probanza de méritos (1602)1 Sonia Kania (bio) In April 1602, Vicente de Zaldívar, a nephew of Juan de Oñate and one of his principal officers, appeared before the authorities in Mexico City to plead for the New Mexico campaign. The colonization effort of this part of the northern frontier of New Spain found itself in dire straits as many of the colonists, disillusioned with the state of affairs, had abandoned the fledgling capital of San Gabriel2 while Oñate and company were exploring the land of Quivira from June to November 1601 (see below). Although Zaldívar was sent to apprehend the traitors before they reached the safety of New Spain, he was unsuccessful and was thus sent to Mexico City to do damage control. He had to defend Oñate’s actions against the accusation of the deserters and, at the same time, petition for more troops in order to more successfully control and explore the territory. The Probanza de méritos was assembled as part of the bureaucratic process to prove the worthiness of the enterprise and of its principal players. The text can be divided into four parts, each containing a separate interrogatory with witness responses regarding the services and merits of Vicente de Zaldívar in the posts he occupied. Part 3 represents witness responses to a series of twelve questions posed by Zaldívar relating mainly to his services as maestre de campo, or second in command under Oñate.3 A significant number of the questions of Part 3 (Questions 6–10) deal with the journey to Quivira.4 It would therefore be beneficial to outline the principal events of the expedition.5 Oñate learned of Quivira from Jusepe, a Mexican Indian and survivor of the Leyva-Humaña expedition of 1593 who presented himself in the then-capital of San Juan sometime before February 1599. More than two years elapsed before Oñate and his men finally departed for Quivira. [End Page 295] In the intervening time, the Spaniards had more local troubles to deal with in the form of Indian unrest and uprisings—there was serious fighting with the Acomans in late 1598 and early 1599 and conflicts with the Jumanos of Abó in late 1600 and early 1601.6 The colonists certainly must have felt uncomfortable with the idea of a prolonged absence of a significant contingent of the colony, as would occur on an expedition. The battles with the native groups underscored the need for reinforcements for the New Mexico enterprise. These finally arrived on Christmas Eve 1600. If not the colony as a whole, Oñate, at least, felt that the time was right for the much-anticipated trip to Quivira. Oñate and his party embarked on the journey on June 23, 1601. They traveled more than 200 leagues in a northeasterly direction to what is present-day Kansas, south of Wichita. Before reaching the great settlement (gran población) of Quivira, the Spaniards came upon a nomadic group living in rancherías, or tepee camps, whom they named the Escanxaques. The Escanxaques were enemies of the Quivirans and accompanied Oñate on what remained of the journey to the first settled community of the latter group.7 Having been told that the Oñate party was investigating the fate of the Leyva-Humaña camp, the Escanxaques believed that the Spaniards were seeking revenge on the Quivirans and were hoping to capitalize on the ensuing conflict. Spaniards, Escanxaques, and Quivirans came into contact on the outskirts of the first Quiviran settlement. At first the encounter was peaceful, but Oñate, informed by the Escanxaques that the Quivirans had killed members of the Leyva-Humaña expedition and were holding one member captive, proceeded to take hostages to serve as guides, among them the apparent chieftain of the Quiviran village. When the Spaniards and their escorts finally arrived in the first settlement, they found that it had been abandoned. The inhabitants had ostensibly been warned of the Spaniards’ approach and had fled to safety, perhaps with the...

Effect of Permeability Coefficient of Reservoir Bank Slope on Pile Displacement and Ground Deformation

Due to effect of reservoir water, the deformation mechanism of reservoir bank slope has a great of influence to the buildings which locate on the bank slope. Considering the changes of permeability coefficient of ground, the deformation characteristics of bank slope ground and pile are analyzed based on the method of pile-soil interaction under the condition that the reservoir water level changing speed is invariable. The results revealed that the larger horizontal displacement of the ground and piles happened when the ground has a smaller permeability coefficient, and the larger settlement of the ground and pile happened, especially the pile which has greater differential settlement when the permeability coefficient of ground is larger. The results have certain reference significance on the safety evaluation and design of buildings which locate on reservoir bank slope.

Green sea urchins structure invertebrate and macroalgal communities in the Magellan Strait, southern Chile

Although sea urchins play a central role in determining the structure and functioning of macroalgal communities in many parts of the world, past research in southern Chile has failed to identify strong effects of urchin grazing, despite the prevalence of coralline-dominated commu- nities and abundant urchins, which indicate a likely structuring role for urchins. Here, we con- ducted experimental removals of the most common urchin, the green sea urchin Arbacia dufres- nii, on a single bedrock wall in the Magellan Strait, Chile. We monitored the responses of invertebrate and macroalgal communities relative to a control wall 6 times over 64 wk. The struc- ture of macroalgal communities on each wall remained similar until more than 40 wk after urchin removal, at which time the community structure diverged, with significantly more macroalgae present on the urchin removal wall. These changes coincided with the onset of early summer and were likely driven by greater settlement, recruitment and growth of algae in the absence of urchins. After 64 wk, the abundance of chitons, bryozoans, mussels and the small bivalve Hiatella solida was also significantly greater on the urchin removal wall. Herbivory by A. dufresnii on these high latitude rocky reefs appears to have a potential structuring effect on benthic assem- blages, although further replicated field experiments are required to document where and when these effects may occur.