Settlement Values Research Articles

Field Monitoring Analysis of Construction Process of Deep Foundation Pit at Subway Station

Taking the excavation of deep foundation pit of a subway station in Ji’nan city as the background, and the measured data of the deep-horizontal displacement, support axis force and the surface settlement of the retaining pile body during the excavation was analyzed. It was shown that with the increase of excavation depth of the foundation pit, the position of the maximum horizontal displacement of the pile gradually moved downward from the top of the pile, and the pile deformation curve gradually changed from a similar cantilever beam to a “bow shaped” curve, the phenomenon of moving to the outside of the pit occurred at the top of the pile in the end-well of subway station. It is necessary to prevent the first reinforced concrete support and the retaining structure from being broken due to the lateral displacement of the top of the pile. The foundation pit excavation caused the settlement of the surrounding surface. The maximum settlement point was about 15 m from the boundary of foundation pit. The maximum surface settlement value was located in the middle of the standard section. The maximum settlement was 18.5 mm. The maximum horizontal displacement of ZQT37 measuring point at the standard section was 23.79 mm, and the location of maximum horizontal displacement was approximately 17 m from the top of the foundation pit. The axial force of the concrete support and the third steel supports at the ZCL20 section of the standard section were the largest. All supports were in safe working condition during excavation of the foundation pit.

Effect Analysis of Delay Time on Strength of Cement Stabilized Mixture

To improve the efficiency of construction, reduce the curing period, it’s necessary to determine the effect of delay time on the strength of cement stabilized mixtures. Through indoor simulated test and one-time vibration forming of specimen, which is control of different vibration time and degree of compaction, the cement stabilized specimens with different compactness are delayed 0 to 15h respectively. Test 7d unconfined compressive strength, elastic modulus, splitting strength and so on. Compared with different models, different places of retarded cement, coarse aggregate and fine aggregate, and it is delayed by 0 ~ 168h respectively. Then analyze 7 days unconfined compressive strength and secondary vibration settlement value. The test results show that delayed vibration 12h secondary compression can still increase the intensity. Under the same compaction degree (98%), there is a boundary point (delay vibration in 9h∼12h), the specimen compressive strength, compressive elastic modulus, splitting strength are higher than the respective reference value.

Simple design models for bearing ratio of sand reinforced using different geosynthetics

To develop relatively simple equations for design of a reinforced pavement design model, tests were conducted. Firstly, the effects of vertical spacing of reinforcement layers and depth of the reinforced zone were investigated by using different types of geosynthetic materials. The number of the reinforcement layers was also varied to see how these material parameters influenced the results. The comprehensive results from laboratory model tests supported on a woven geotextile and different geogrids were presented. The results were compared to each other. Based on model tests, different reinforcement types showed different behaviors for different numbers of reinforcement layers and different vertical spacing of the reinforcement layers. Additionally, it was seen that the improvement obtained by reinforcing the subgrade is different for low settlement ratio values and large settlement values for different vertical spacing values. Then, new simple estimation formulas were determined for bearing ratio by regression analyses for different types of reinforcement materials.

Medical Malpractice in Orthopedic Surgery: A Westlaw-Based Demographic Analysis.

A recent study that evaluated the risk of facing a malpractice claim by physician specialty found that orthopedic surgeons were at a significantly greater risk of being sued than other medical specialists. To date, no studies have characterized trends in orthopedic surgery malpractice claims. The Westlaw legal database was used to locate state and federal jury verdicts and settlements related to medical malpractice and orthopedic surgery from 2010 to 2016. Eighty-one cases were analyzed. The mean age of the affected patients and/or plaintiffs was 53.4 years. Spine surgery (21 cases; 25.9%), knee surgery (17 cases; 21.0%), and hip surgery (11 cases; 13.6%) were litigated most often. Procedural error (71 cases; 87.7%) and negligence (58 cases; 71.6%) were the 2 most commonly cited reasons for litigation. The jury found in favor of the defendant in most (50 cases; 61.7%) of the cases. The mean plaintiff (17 cases; 21.0%) verdict payout was $3,015,872, and the mean settlement (13 cases; 16.0%) value was $1,570,833. Unnecessary surgery (odds ratio [OR], 12.29; 95% confidence interval [CI], 1.91-108.46; P=.040) and surgery resulting in death (OR, 26.26; 95% CI, 2.55-497.42; P=.040) were significant predictors of a verdict in favor of the plaintiff. Patient death (OR, 0.05; 95% CI, 0.01-0.38; P=.021) and male patient sex (OR, 0.26; 95% CI, 0.09-0.71; P=.033) were significant negative predictors of a verdict in favor of the defendant. The jury found in favor of the defendant orthopedic surgeon in most cases. Procedural error and/or negligence were cited most commonly by the plaintiffs as the bases for the claims. Verdicts in favor of the plaintiffs resulted in payouts nearly double those of settlements. [Orthopedics. 2018; 41(5):e615-e620.].

Settlement and Load Transfer Mechanism of Pipeline Due to Twin Stacked Tunneling with Different Construction Sequences

The tunnel-pipeline-soil interaction is attracting more and more wide range of scholars and was treated as a plane strain problem, with little attention given to the responses of existing pipeline to twin-tunneling process with different construction sequences. Moreover, there are rare reports available on the influences of tunnel construction sequences on an existing pipeline. In this study, a three-dimensional centrifuge model test and numerical simulations using an advanced hypoplasticity constitutive model were conducted to investigate the influences of twin stacked tunneling with different construction sequences on an existing pipeline. The results shows that the maximum values of greenfield ground settlement, pipeline settlement and additional pipeline bending strain due to twin stacked tunneling when the upper tunnel was excavated first were 25%, 18% and 11% larger, respectively, than those when the lower tunnel was excavated first. The maximum values of greenfield ground settlement, pipeline settlement and additional pipeline bending strain due to twin stacked tunneling when the lower tunnel was excavated first were slightly smaller than those when the twin tunnels were excavated simultaneously. After the twin-tunneling process, the sagging regions were located within ± 1.5DT (tunnel diameter) in these three conditions. The maximum pipeline bending strain within the hogging regions was approximately half of that within the sagging regions. Because of shielding effects from the upper tunnel, the region where vertical stress of the soil reduced was transferred to both sides of the tunnel due to the second tunneling process when the upper tunnel was excavated first. As a result, the extended sagging regions due to the second tunneling process when the upper tunnel was excavated first were two times than that when the lower tunnel was excavated first.

Settlement prediction for protected buildings nearby deep excavation

Increasing demand on new spaces in cities due to restrained urban conditions dictates development of underground construction including excavation of deep pits. So there is a need to prevent negative consequences caused by changes in a stress-strain condition of soil mass and additional settlement of foundations with underlying soil. A decrease in excessive settlements of building and their difference could be achieved by protection of a building with implementation of mitigation measures. The goal of the paper is to provide a method of settlement prediction for adjacent buildings in a zone of deep pit excavation for mitigation measure – underpinning of foundations with micropiles. Different factors affecting the settlement value (of building with micropiles) were considered. These factors are the distance from pit edge to a building, geology type, depth of excavation, height of the building etc. Also variation of settlement along a building was taken into account. A series of numerical experiments was conducted modelling these conditions. By methods of statistical analysis empirical equations were obtained allowing to predict the settlement of adjacent buildings underpinned with micropiles. These equations serve as a base for method aimed to determine building settlement in a zone of deep excavations impact with micropiles installed, also considering technological settlement. Technological settlement values were taken from similar case histories. Settlement prediction with the use of obtained equations could be useful at initial design phase to evaluate the use of micropiles to ensure permissible additional settlement values of adjacent buildings in a zone of deep excavation impact.

Designing singular jet grouting column for sandy soils

In this study, the bearing capacity and settlement values of jet grouting columns with the same diameter in very loose and loose sandy soils were estimated by theoretical approaches and numerical analysis depending on the change in the length of the jet grout columns and soil relative densities, and those values were compared with each other. The changes in bearing capacity and settlement values obtained from soil parameters, jet grouting column length and method differences were examined. In the designing of the jet grouting column, these factors should be determined carefully and correctly. The bearing capacity of the jet grouting column is calculated by the theoretical approach considering as a pile. The settlement values of the jet grouting column were calculated by semi-empirical, empirical and theoretical methods. In numerical analyses, single jet grouting column was modelled with Mohr Coulomb and Hardening Soil models in axial symmetry model and the bearing capacity and settlement values of singular jet grouting column were determined.

CORRECTION OF IMITATING MODELS OF BIOEFFICIENCY OF GRAIN CROPS WITH USE OF THE DATA OF REMOTE SOUNDING

In article the method of correction of results of imitating models of bioefficiency of grain crops is offered by the example of a winter wheat on the basis are no viscous modeling calculations of an index of sheet surface LAI (Leaf Area Index) and hisvalues designed calculated оn the datato remote sounding (DRS) of agricultural fields. Calculations of bioefficiency of a winter wheat with use of mechanistic model WOFOST and updating of settlement values of a sheet index (LAI) are executed on the basis of a satellite estimation of a vegetative index. In view of correction of results with use DRS accuracy of the forecast of productivity makes about 1,68 c/h.

Proximal fibular osteotomy to treat medial compartment knee osteoarthritis: Preoperational factors for short-term prognosis.

ObjectiveThe purpose of this study was to determine the association between preoperational factors and patients’ short-term outcome after proximal fibular osteotomy (PFO) and to provide a basis for detailed surgical indication and patient selection.MethodsThis was a retrospective study of patients undergoing PFO between January 2015 and December 2015. Preoperational clinical data including gender, age, duration of disease, visual analogue score (VAS) and American Knee Society (KSS) score were collected. The radiological factors including hip-knee-ankle angle (HKA angle), condyle-plateau angle (CP angle), Kellgren and Lawrence grade (KL grade), joint space width of both compartments and settlement value were also considered. Patients were followed for at 12 months postoperatively. Both clinical and functional KSS scores were obtained. The outcome of interest was divided into clinical outcome and functional outcome. For each, two criteria were defined: satisfaction and significant improvement. Satisfaction is characterized by a KSS clinical or functional score over 70 points (excellent and good results); significant improvement refers to an increase in KSS scores of more than 15 points. Bivariate logistic regression for the association between preoperational factors and outcomes of interest was performed. Multivariable logistic regression analyses were used to detect the independent factors affecting the outcomes.ResultsA total of 84 patients and 111 knees were followed-up. Of these, 17 knees were from males and 94 were from females. The average age was 59.45±8.82 years. The average preoperational VAS score, KSS clinical and functional score were 7.08±1.41 points, 49.14±10.95 points and 44.97±17.71 points, respectively. According to KL grading, there were 17 knees of grade 2, 47 knees of grade 3, and 47 knees of grade 4. In clinical outcomes, there were 51 knees in the satisfaction group and 77 knees in the significant improvement group. In functional outcomes, 43 knees were in the satisfaction group and 76 knees in the significant improvement group. KSS clinical score (OR = 1.134, 95%CI = 1.067–1.205, P = 0.000) was the independent factor associated with clinical satisfaction. Age (OR = 1.072, 95%CI = 1.000–1.150, P = 0.048), VAS score (OR = 1.679, 95%CI = 1.041–2.706, P = 0.033), KSS clinical (OR = 1.072, 95%CI = 1.005–1.144, P = 0.034) and functional (OR = 1.100, 95%CI = 1.044–1.159, P = 0.000) score, HKA angle (OR = 1.345, 95%CI = 1.119–1.617, P = 0.002) and settlement value (OR = 7.540, 95%CI = 1.307–43.484, P = 0.024) were the independent factors associated with functional satisfaction. KSS clinical (OR = 0.905, 95%CI = 0.850–0.963, P = 0.002) score, CP angle (OR = 0.760, 95%CI = 0.593–0.973, P = 0.030) and medial joint space width (OR = 0.001, 95%CI = 0.000–0.107, P = 0.003) were the independent factors associated with significant clinical improvement; VAS score (OR = 1.582, 95%CI = 1.042–2.402, P = 0.031), KSS functional (OR = 0.888, 95%CI = 0.838–0.942, P = 0.000) score, HKA angle (OR = 1.292, 95%CI = 1.101–1.518, P = 0.002) and settlement value (OR = 9.990, 95%CI = 1.485–67.197, P = 0.018) were the independent factors associated with significant functional improvement.ConclusionsThe independent factors affecting postoperative clinical outcome after PFO were KSS clinical score, CP angle and medial joint space width. In addition, the independent factors that influenced functional outcome included age, VAS score, KSS score, HKA angle and settlement value. As objective radiological evidence, HKA angle and settlement value could be used as an important basis for patient selection for PFO.

Piled Raft Design Approach for a High Rise Building on Tithal Road, Valsad, Gujarat

ABSTRACT The piled raft foundation has been efficiently used for the foundation of high rise structures. A typical high rise building generally imparts higher load on central core area due to existence of lifts, elevators and shear walls, comparison to the edge area. The shallow foundation may not control the settlement and the pile foundation cost may be expansive for the foundation of high rise structures. The piled raft foundation can reduce the total settlement as well as differential settlement effectively with a good economic performance. The components of a piled raft foundation should be designed in such a way that it can withstand the non-uniform load of a typical high rise building. The parametric numerical study has been carried out for the different piled raft configurations to propose the foundation of a 14 storey high rise building under Gujarat housing board project on Tithal road, Valsad. The present numerical study is based on the preliminary design strategies of piled raft foundation serving the settlement criteria as well as economic performance of the chosen arrangement of piled raft configurations. All the configurations of piled raft foundation were studied in the terms of maximum settlement, differential settlement, bending moment and pile axial load. The study shows that the reduction in the pile length at specified position was found effective to reduce the overall cost of construction, whereas the permissible values of settlements were always obeyed. Plaxis 3D finite element tool has been adopted for the present numerical analysis. Keywords: Pile, Raft, Settlement, Differential settlement, Pile axial load, Optimization Cite this Article Uttam Kumar, Vasanwala SA. Piled Raft Design Approach for a High Rise Building on Tithal Road, Valsad, Gujarat. Journal of Geotechnical Engineering . 2018; 5(1): 1–10p.

Prediction of Long-Term Seawall Settlement Based on Least Squares Support Vector Machine

In this study, the basic principle of the least squares support vector machine (LS- SVM) method was introduced systematically. The method was applied in a seawall engineering project to establish a prediction model of long-term seawall settlement based on the LS-SVM method, and the model parameters were optimized based on the genetic algorithm. Based on the monitoring data of seawall settlement during the construction of a soft foundation seawall project in Wenzhou, China, a sample was selected to train the model, and the predicted value of long-term settlement calculated by the model was compared with the measured sample value. The results show that, with highly accurate and reliable prediction results, the prediction model of long-term seawall settlement based on the LS-SVM method possesses great application value.

Study of the behaviour of skirted shallow foundations resting on sand

The performance of skirted shallow foundations resting on sand bed was investigated using physical modelling. Laboratory tests were performed on small-scale foundation models to study the behaviour of circular, skirted foundations subjected to vertical loads. The effects of foundation diameter, relative density of sand, skirt depth and roughness of the model surface on the bearing capacity and settlement of skirted foundations were studied. The results of the model tests have shown that using skirts improve the bearing capacity and settlement values of skirted foundations compared with shallow foundations without skirt. The improvement in bearing capacity and a reduction in settlement of shallow foundations increase with increasing the skirt depth, roughness of skirt sides and decreasing the relative density of sand. The ultimate bearing capacity of shallow foundations may be increased by up to 5·0 times and the settlement can be reduced to a value of 8% of those of foundations without skirts. On the basis of the obtained results, a series of charts are presented to estimate bearing capacity improvement and settlement reduction in terms of sand relative density, skirt depth to foundation diameter ratio and roughness of skirt sides. Skirted foundations resting on loose sand are more beneficial than those resting on medium and dense sand.

Analysis of Negative Skin-Friction on Single Piles by One-Dimensional Consolidation Model Test

The computer program pile negative skin friction (PileNSF) was developed by the authors to predict the bearing capacity of a pile embedded in a consolidating ground due to surcharge loading. The program uses a one-dimensional analytical soil-pile model, which was formulated based on the nonlinear load-transfer method and Mikasa’s generalized one-dimensional consolidation theory. To investigate the development of negative skin friction on single piles, as well as to validate the computer program (PileNSF), a laboratory model test was performed in this study. The clay layer was subjected to increasing surcharge loads to simulate actual field conditions. Results showed that as excess pore pressure decreases and as surcharge load increases, the dragload and downdrag on pile increases. The measured values of soil settlement, excess pore water pressure, and axial force on pile were compared with the predicted values obtained from the computer program. The results of the computer program (PileNSF) showed to be in good agreement with the measured data. Therefore, negative skin friction on single piles can be effectively predicted using the computer program, PileNSF, provided that reasonable parameters are used in the analysis. After validating the program, a parametric study was carried out to study the influence of various pile design parameters on negative skin friction.

Studying seismic interaction of piles row-sandy slope under one, two and triaxial loadings: a numerical-experimental approach

In this paper, the seismic behaviour of the floating piles row was installed into a loose dry sandy slope by help of 3D numerical simulations has been studied. A parametric 3D numerical modelling is conducted within the framework of the finite difference method. Both near-fault and far-field earthquakes have been applied to derive new relationships between shear forces generated in piles and depth along the piles under effects of the one, two and triaxial seismic loadings in the large-scale numerical models of sandy slope-floating piles row. As an innovation, the pattern and the amount of lateral displacements as well as the generated shear forces in the piles row are calculated under effects of the NF and FF records. In addition, the increase values of slope settlement have been investigated under two and triaxial seismic loadings compared to conventional uniaxial loading. The validation of the results obtained by numerical method was controlled using the investigation of the slope settlements reinforced by a piles row with the help of shaking table and a good agreement was observed between the numerical and experimental results.

Test fill brought to failure on soft plastic marine clay at Onsøy, Norway

A test fill at Onsøy, close to the town of Fredrikstad in Norway, was built on a very soft marine clay with in situ vane strength as low as 11 kPa and a plasticity index varying from 34 to 50. The dimensions at the bottom of the long test fill were 20 m × 60 m with a height of 2.3 m. The fill, as placed in the first stage, had a computed factor of safety against foundation failure of 1.35 based on in situ vane strength. The fill was allowed to sit for about 3 years (from 1972 to 1975) before it was, in a second stage, brought to failure in about 4.3 days by raising the height. This second stage is the subject of this paper. Back-calculation of the failure by undrained stability analysis based on in situ vane tests performed shortly before the start of the second stage, based on undrained triaxial and constant volume direct simple shear tests on specimens from tube samples taken shortly before the start of the second stage and reconsolidated to the in situ effective stresses, gave factors of safety varying from 0.88 to 1.45 depending on type of analysis. Settlement values computed at the centreline of the fill for the second stage based on the results from undrained compression triaxial tests agreed reasonably well with the field measurements.

Effect of Geocell Reinforcement above Buried Pipes on Surface Settlement

This paper presents an experimental study on the effect of geocell reinforcement on the soil surface settlement. A number of laboratory experiments were conducted using PVC pipes which were buried in medium sand layer and below a subbase layer reinforced with geocells. The model is subjected to dynamic repeated loading with different amplitudes (0.5 ton and 1 ton) and different loading frequencies (0.5 Hz, 1 Hz, 2 Hz) to study the effects of the of geocell reinforcement layer inclusion on the surface settlement. The results of the experimental work showed that the surface settlement increases with the increase of the load amplitude. The reduction of surface settlement due to the geocell reinforcement is about 29 to 43 % when the amplitude of load is 0.5 ton, and this value becomes 32 to 41 % when the amplitude of load is up to (1) ton. The surface settlement value increases proportionally with the increment of frequency amplitude for every tested model. When increasing the frequency of loading from 0.5 Hz to 2 Hz, the soil surface settlement value increased by 47 % for the models with no geocells and by 57 % for geocell reinforced models.

Study on construction technology of metro tunnel under a glass curtain wall

To ensure the safety of the glass curtain wall building above loess tunnel and get an optimal scheme, an elastic-plastic FEM model is established to simulate three reinforcement schemes based on a tunnel section in Xi’an Metro Line 3. The results show that the settlement value of the optimal scheme is reduced by 69.89% compared with the drainage measures, and the uneven settlement value is reduced by 57.5%. The construction points, technical processes and technical indexes of the optimal scheme are introduced. According to the actual project, the cumulative settlement of the building under construction is 16mm, which meets the control standards. According to the actual project, the cumulative settlement of the glass curtain wall building is 16mm, which meets the control standards. The reinforcement scheme can provide some reference for the design and construction of the metro in loess area.

COMPARISON OF ACTUAL GROUND SETTLEMENTS IN TUNNELLING EXCAVATION TO MODEL PREDICTIONS

It has been discovered that the underground structures are vulnerable to seismic phenomena mainly due to permanent ground deformations caused by earthquakes rather than the dynamic seismic movement itself. Several models (empirical formulae) have been developed to estimate such deformations. In this paper, measured settlements from the tunnelling excavation for the extension of Line 3 of the Athens Metro (from Egaleo station to Chaidari) are used for the verification and calibration of such formulae. Firstly, some general information is presented concerning the progress of Line 3 so far. Typical buildings, infrastructure and utility grids that can affect the design and construction of the tunnel are examined. Typical geological, hydrogeological and geotechnical conditions along the axis of the excavation, as specified by laboratory tests, are presented as well. According to these conditions, ground settlements are predicted along the tunnel. Secondly, a comparison is made of the actual values of the ground settlements, which come from geotechnical and structured observations, and the estimates provided by the empirical formulae. Some improvements are proposed for this formulae through the RS2 software program (Phase 2 v.9.0) by Rocsience. The improved model is then used to estimate strains that could be induced by future earthquakes.

Effect of Inherent Anisotropy on the Behavior of Fine-Grained Cohesive Soils

Study on shear strength and compressibility characteristics of soils considering anisotropy phenomenon is essential to the accurate design of structure foundations and stability analysis of earth structures. In this research, a series of triaxial and oedometer tests were used to study the mechanical behavior of a fine-grained cohesive soil considering the effect of inherent anisotropy on the behavior. For this purpose, a special soil sampler was made and different directions were selected to collect the samples from the site. All triaxial samples were isotropically consolidated under the effective stresses of 200, 300 and 500 kPa, and loaded at the rate of 0.05 mm/min. The results showed that the shear strength and compressibility of the soil intensively depend on the sampling direction. With an increase in the anisotropic angle, the shear strength values decreased and the settlement values increased. However, at the anisotropic angle of 72°, the shear strength and settlement have minimum and maximum values, respectively. In addition, a review of failure surface illustrates that as the angle between the failure surface and the bedding direction decreases, the failure surface tends to be closer to soil stratification and it causes an increment in pore water pressure and reduction in shear strength. In general, samples cored perpendicular to the bedding direction showed dilative behavior, whereas the other ones exhibited contractive behavior.

Numerical simulation of the composite foundation of cement soil mixing piles using FLAC3D

In the road construction process often encountered in the construction of the phenomenon in the soft soil area, due to the physical properties of soft soil often can not meet the design requirements, it is often on the soft ground to add additives to achieve a more solid foundation. In order to compare the settlement of two different piles to determine a more suitable engineering method.The silty soft soil foundation of Xinxicheng Road was numerically simulated by the software of FLAC$$^\mathrm{3D}$$, and a single-pile model was established to simulate the load test of single pile by loading load step by step. The resulting deformation grid diagrams of the cement soil mixing pile and cement sand soil mixing pile under loads of 300 kPa indicate that deformation gradually decreases from the center to the surrounding, and the maximum settlements of the two deformation maps were 19.36 and 13.60 mm, respectively. The relationships between maximum settlement and load show that the settlement values of the cement soil pile and cement sand soil pile were similar (within 1–2 mm of each other). The settlement value of the cement sand soil mixing pile was smaller than that of the cement soil mixing pile under large loads. Therefore, the use of cement sand soil piles can reduce the maximum settlement to meet engineering requirements. This paper provides a theoretical basis and guidance for the future treatment of soft ground deformation.