Mucky Soil Research Articles

Intelligent approach for mucky soil identification during shield tunnelling by enhanced YOLO model

An efficient determination of the geological characteristics and soil-rock type ahead of a tunnel face is critical for adjusting construction parameters during shield tunnelling. In general, operational engineers rely on visual observations of mucky soil types from belt conveyors. This results in shield halting and involves both time and cost implications. This paper proposes a deep learning approach designed to identify mucky soil by monitoring a video installed on the strut of a belt conveyer. The proposed approach comprises four steps: (1) image acquisition, (2) enhanced you-only-look-once (YOLO) modelling, (3) model performance evaluation, and (4) soil identification based on an optimal analysis. The enhanced YOLO model is a deep image detection algorithm. It was introduced by integrating two innovative strategies: data augmentation and imbalance learning. This enhancement accelerates the speed of image identification and improves the overall classification performance. A case study of shield tunnelling in the soil-rock mixed strata of the Guangzhou–Foshan intercity railway line was conducted to validate the proposed approach. The results indicate that the enhanced YOLO model achieves a classification performance comparable to that of the highly optimised AlexNet and GoogleNet. Additionally, the proposed approach more effectively detects the muck soil content than manual observation. This demonstrates its potential for real-time applications in shield tunnelling operations.

Time-domain dynamic constitutive model suitable for mucky soil site seismic response

Time-domain dynamic constitutive model suitable for mucky soil site seismic response

In situ digital testing method for quality assessment of soft soil improvement with polyurethane

This study purposes an in situ testing method on quality assessment of soil improvement. Factual drilling data includes the spatial distribution and in situ strength of untreated and treated soil along three different drillholes measured by on-site drilling monitoring method. These factual drilling data can characterize the degree of soil improvement by penetration injection with permeable polyurethane. Result from on-site drilling monitoring shows that the linear zones represent constant drilling speeds shown in the plot of drill bit advancement vs. net drilling time, which indicates the spatial distributions of soil profile. The soil profile at the study site is composed of four layers, which includes fill, untreated silty clay, treated silty clay, and mucky soil. The results of soil profile are verified by the parallel site loggings. The constant drilling speeds profile the coring-resistant strength of drilled soils. By comparing with the untreated silty clay, the constant drilling speeds of the treated silty clay have been decreased by 13.0–62.8%. Two drilling-speed-based indices of 61.2% and 65.6% are proposed to assess the decreased average drilling speed and the increased in situ strength of treated silty clay. Laboratory tests, i.e. uniaxial compressive strength (UCS) test, have been performed with core sample to investigate and characterize in situ strength by comparing that with drilling speeds. Results show that the average predicted strengths of treated silty clay are 2.4–6.9 times higher than the average measured strength of untreated silty clay. The UCS-based indices of 374.5% and 344.2% verified the quality assessment (QA) results by this new in situ method. This method provides a cost-effective tool for quality assessment of soil improvement by utilizing the digital drilling data.

Settlement Calculation Method for Peat Soil Foundations

The calculation of the settlement of a peat soil foundation is based mainly on the formula obtained by data fitting or simply modifying the universal calculation formula. The deformation mechanism reflected by these calculation methods is indistinct. Therefore, several model tests were carried out using the embankment structure of the Dali–Lijiang expressway as a prototype, and the settlement was analyzed with the one-way consolidation deformation and in situ settlement of other researchers. First, the S − logt (S is the deformation) curve of peat soil showed no obvious inverse “S” change, which is different from that of soft soil or mucky soil. According to the S − t curve, the deformation process of peat soil can be divided into three stages. Second, the relationship between the compression modulus and load was analyzed and combined with the settlement calculation results. The compressive modulus between 12.5 and 25 kPa [En(0.125–0.25)] was proposed to be used when calculating the settlement of peat soil foundations by the layerwise summation method. Moreover, the compression modulus of the three consolidation stages was proposed to be used to calculate the settlement of peat soil foundations by the layered sum method. At the same time, the influence of confinement on the compression modulus of the third consolidation stage should be considered and corrected. The accuracy of the settlement calculation method proposed in this paper was higher than the accuracy of the standard layerwise summation method, regardless of whether the horizontal limiting conditions of the standard method are modified.

Field monitoring and analysis of soil deformation of curved steel pipe jacking in Gongbei tunnel

To ascertain the soil deformation law in the construction of curved pipe jacking, ground deformation, layered settlement and lateral deformation of deep soil have been analyzed by field monitoring of soil deformation data in different types of soil in the curved pipe jacking roof of Gongbei tunnel. The results show that the curved pipe jacking induced ground settlement groove curve shows asymmetry. The variation law of ground settlement and deep soil deformation in different soil is consistent, and the mud pressure, excavation face support force and friction resistance have great influence on the deep soil deformation, but the maximum deformation is related to the soil type. Adjacent curved pipe jacking construction will cause the accumulative deformation of surrounding soil, due to the supporting effect of the completed pipe jacking on surrounding soil, the accumulated value of this part of soil is small. The maximum settlement values of single curved pipe jacking are artificially fill > sand layer > mucky soil. during construction of adjacent jacking pipes, the cumulative deformation values are as follows: mucky soil > artificial fill > sand layer, indicating that the deformation of mucky soil is more significant under multiple disturbances. The soil loss caused by relative position of curved pipe jacking and tunnel is the main reason for the ground settlement deviation. The calculated result of modified Peck formula is accordance with measured values, which can be used to predicate the surface deformation caused by curved pipe jacking.

Investigation on the Stratigraphic Response and Plugging Effect Induced by Press-In Open Caisson in Mucky Soil

Press-in open caisson method, which sinks into soil with the aid of mechanical pressure without excavation, is becoming an important method of construction in extremely soft foundations. However, many engineering problems are prone to occur in the construction of caissons, such as sinking and large deformation. In this study, the stratigraphic response model, such as soil migration during the press-in process of open caisson, is focused on. Through model tests of soil and caissons, the migration patterns of each part of the soil were carried out, and the mechanism underlying the stratigraphic response pattern was investigated. The three primary conclusions are as follows: 1) The bottom edge foot of caisson produces lateral extrusion on surrounding soil in the range of 10 cm (20%H) below, resulting in lateral movement of soil. 2) two kinds of plug, i.e., “wedged” and “unwedged” plugs exist, and the driven forces for the soil migration can be divided into three stages, i.e., caused by soil plug with active arch, by soil plug with passive arch and caused by soil squeezing effect. 3) there is a significant linear correlation between the soil plug changes, the horizontal movement of the deep soil body, and the displacement of the surface uplift. The soil plugging effect and squeezing effect are interacted and enhanced with each other. This study provides a new understanding of the stratigraphic response in the construction of press-in open caissons, and guides safety control of open caissons construction.

Mechanical response of diaphragm wall supporting deep launch shaft induced by braced excavation and pipe jacking operation

The stability of braced structures for the launch pit in pipe jacking plays a vital role in structural safety during excavation and jacking drive. Through a deep launch pit in Foshan, the real-time deformation and mechanical response of the diaphragm walls, internal struts, and the soil behind the wall induced by braced excavation and pipe jacking operation are obtained from in-situ monitoring and three-dimensional finite element model. The internal struts restrict the further wall deflection and earth pressure in the braced excavation, displaying the apparent time–space effect or corner effect of the limited-scale & deep launch pit. Moreover, pipe jacking operation influences the reaction wall within a certain zone, contributing to the apparent spatial effect. The outward deformation and the increase in the soil pressure occurred in the disturbed zone. Although part of the mucky soil reaches the ultimate equilibrium during the deep excavation and jacking drive, the diaphragm walls still indicate superior strength and stiffness.

Experimental short-time wildfire simulation—Physicochemical changes of forest mucky topsoil

Today, fires constitute one of the most important factors that can affect soil properties, acting at a rapid pace and on a large scale. They often result from climate change. The present study was aimed at examining how water capacity as well as carbon and nitrogen concentration change during a simulated fire of forest mucky soil under laboratory conditions. The combustion was carried out in two short-time variants—for 3 and 9 min. The results presented herewith show that even a short-term fire of the soil cover contributes to visible changes in the physicochemical parameters of the soil. Thermal decomposition of organic matter caused an increase in total carbon and nitrogen concentrations and a slight increase in the Ct/Nt ratio. The burning of soil samples caused a slight upward trend in soil pH and this was associated with soil organic matter (SOM) deprotonation. The experiment showed the effect of mucky soil burning on the change of its water relations. The 3-min combustion significantly increased the maximum water storage capacity (both after 4 and after 24 h of immersion in water), while the 9-min combustion showed significantly worse results.

Movements and Habitat Use of Bog Turtles in a Southern Appalachian Bog

Habitat loss from human activity and vegetative succession is a major threat to the imperiled Glyptemys muhlenbergii (Bog Turtle). In its southern range, most remaining populations are in open-canopy wetlands with emergent vegetation and a history of livestock grazing. To better understand the natural history of Bog Turtles in an understudied habitat, we studied the movements and habitat use of Bog Turtles in a Castor canadensis (American Beaver)-maintained southern Appalachian bog in North Carolina with no known grazing history and a predominance of shrub/scrub habitat. We tracked 6 adults (4 female, 2 male) using radio telemetry from May to November 2015, calculated daily movement rate and home range, and investigated vegetation and soil components of habitat selection. Our results suggest wetlands with substantial shrub/scrub macrohabitat should be considered potentially suitable Bog Turtle habitat if emergent macrohabitat for nesting and deep, mucky soil are also present. The relative roles of vegetation and soil in habitat selection need further investigation.

Controlling Conditions of the One-Dimensional Consolidation Test on Peat Soil

This paper studies the changes in the loss on ignition (LOI), total nitrogen content (TN), and strain in a one-dimensional consolidation test on peat soil. The effects of small-range fluctuations in the ambient temperature and changes in the sample height on the consolidation process of peat soil are proposed and verify the inhibitory effect of thymol on the decomposition of organic matter. The results show that when the ambient temperature fluctuates in a small range, the consolidation rate is significantly affected. Under a low load, the ambient temperature increases by 1–2 °C, and the consolidation rate can be increased by up to 10 times. This study presents the changes in loss on ignition (LOI) and total nitrogen content (TN) during consolidation, which proves that soaking the samples with a thymol solution can effectively control the decomposition of organic matter in peat soil. The strain of peat soil at a height of 30 mm is greater than or equal to that of other height samples, while that of mucky soil is 20 mm. Therefore, 30mm is the recommended sample height for peat soil for the one-dimensional consolidation test.

An experimental study of the dynamic compaction method based on relay drainage in foundation treatment of the coastal backfill area

The studies of foundation treatment methods are carried out for the special and complex foundation in the fill, saturated silty fine sand and silt in the coastal backfill area of the coastal zone of the Shandong Peninsula. Based on the economical and efficient dynamic compaction method, the concept of integrated combined drainage is put forward. The relay drainage system of the shallow and deep vertical drainage channels and their relay horizontal drainage channels are designed, and field tests are undertaken. The monitoring data show that under the dynamic compaction load, the relay drainage system can coordinate drainage as a whole, which can quickly discharge the groundwater to dissipate the excess pore water pressure. The rise of groundwater level and dissipation of pore water pressure caused by dynamic compaction can be basically eliminated in about 7 hours. With continuous precipitation, the surface settlement is 0.7%−2.0% of the thickness of the upper soil mass. Under the dynamic load of dynamic compaction, the surface soil is compressed to 8.7%-10.9% of the thickness of the upper soil. The soil settlement is about 5 ‰ and 3 ‰ of the soil thickness at the buried depth of 3−7 m, and 2 ‰ of the soil thickness is at the buried depth of 7−10 m. The test data show that in the effective depth of dynamic compaction, the effect of foundation treatment is obvious, the engineering properties and the degree of consolidation of foundation are improved. The surface bearing capacity and deformation modulus meet the design requirements, the average bearing capacity of silt below 4 m is slightly lower than the design requirements, and the average degree of consolidation of mucky soil is 77%. The monitoring data of one month after tamping shows that the surface subsidence is within 25 mm, which tends to be stable, the layered settlement and pore water pressure are stable and slightly decreased.

A method of calculating the bearing capacity of sand pile composite foundations in a mucky soil layer considering consolidation

In engineering practice, the measured bearing capacity of a sand pile composite foundation in a mucky soil layer is much larger than the design value. Based on the sand pile construction and the load application process, a method of calculating the bearing capacity of the foundation based on the effective stress was proposed. Cavity diameter expansion in sand pile construction was simplified into a planar problem, and the cavity expansion theory was used to establish the expression of the rate of displacement and the horizontal stress increase. Based on the e–p curve and the calculation of the degree of consolidation, the relationships between the horizontal and vertical effective stress and the void ratio were obtained. According to the close relationship between the bearing capacity of the foundation in a mucky soil layer and the water content, an expression describing the relationships between the bearing capacity of the foundation, effective stress, void ratio, and water content was established. For the temporary engineering foundation treatment project, which needs a high bearing capacity but allows large foundation deformation, the design of sand pile composite foundations uses these relationships to take the consolidation effect of mucky soil into consideration, thereby reducing the replacement rate and lowering the construction cost.

Physical and Mechanical Performance of Frozen Rocks and Soil in Different Regions

The artificial freezing method is extensively used in the reinforcement of engineering strata in various regions for shaft excavation and subway connection channels. In this study, representative rock and soil strata from different regions were subjected to low‐temperature physical and mechanical performance tests. The results show that, compared with Cretaceous and Jurassic rock and soil strata, deep topsoil and shallow coastal topsoil have high water content, low thermal conductivities, high frost heave rates, and high freezing temperatures. In addition, the results show that, as the curing temperature decreases, the uniaxial compressive strengths and elastic moduli of deep topsoil and shallow coastal topsoil increase almost linearly. The strength of the sandy soil strata is the highest, followed by the cohesive soil strata, and the strength of the mucky soil and the calcareous clay is the lowest. The strength of the frozen wall and the waterproof requirements must both be taken into account in the freezing design. Deep Cretaceous and Jurassic rocks can have high strength of more than 5 MPa under normal temperature conditions. An increase in the uniaxial compressive strength and elastic modulus with decreasing curing temperature is mainly manifested within the range from the normal temperature to −10°C. The strength can reach more than 10 MPa at −10°C, and only the strength requirements of the frozen wall need to be considered in the freezing design. At low temperatures, deep topsoil and shallow coastal topsoil are dominated by the form of compression failure. The average failure strain at −10°C is typically greater than 5%. When excavating the strata, it is essential to pay attention to the effect of creep. The failure strain of deep Cretaceous and Jurassic rocks is between 1% and 2%, and the breaking and sudden collapse of surrounding rocks should be prevented.

ANALYSIS ON HEAVE-RESISTANT STABILITY CONSIDERING THE EFFECT OF EXCAVATION WIDTH

In recent years, more and more narrow excavations have been executed accompanying the construction of subway stations and underground galleries. The existing calculation methods of heave-resistant stability are mainly based on the soil bearing capacity limit equilibrium theory and slip circle method around the bottom support, ignoring the effect of excavations width. This paper performs numerical simulation of deep foundations under different widths, and puts forward a new model for the calculation of heave-resistant stability in narrow excavation based on the regularity of critical slip surface. The coefficient of passive earth pressure when the width of the backfill is limited is modified. In this case, the paper analyzes the effect of width of excavation and embedded depth of retaining walls. The study shows that the heave-resistant stability of narrow excavation is higher and the effect of width in sandy foundation is more obvious than in mucky soil. The theoretical method is applied to an engineering instance and experimental data confirm its rationality.

Calculation of Tangent Modulus of Soils under Different Stress Paths

During excavation of foundation pit, soils of different sites may undergo different unloading paths. This study focuses on the tangent modulus of soil under different stress paths and provides theoretical basis for the deformation calculation of soil. In this paper, conventional triaxial compression test andK0consolidation unloading test were conducted with mucky soil and silty clay to obtain the deformation characteristics of soils under different stress paths. Experiment results show that the soil samples exhibit distinct stress-strain characteristics under different stress paths, but they all show nonlinearity. The initial tangent modulus increases as the consolidation confining pressure intensifies. Then, based on the test data, the power function relationship between initial tangent modulus and confining pressure under unloading was verified. Simultaneously, a hyperbola function to express stress-strain relation of soils under theK0consolidation unloading condition was proposed and proved. Finally, the formulas of the tangent modulus underK0consolidation unloading were established referring to the derivation of that in Duncan–Chang model. The theoretical calculation results agree well with the test results. It can expand the use of the Duncan–Chang model and improve its application to engineering practice.

The characteristics of microstructure change of sand grain mucky soil under different consolidation pressures

The characteristics of microstructure change of sand grain mucky soil under different consolidation pressures

Evaluation of Engineering Characteristics of Lian-Yan Railway Soft Soil Based on CPTU Data-A Case Study

In this paper, the engineering characteristics of the soft soil in Guan-Yun section of Lian-Yan railway were evaluated based on the CPTU test. The soil layer and classification of soil were performed by using the multi-functional CPTU test. On the basis of results of the CPTU test, the in-situ state parameters including the over consolidation ratio and the undrained shear strength were provided. Simultaneously, the consolidation and permeability characteristics were studied. The results showed that the silt and mucky soil was slightly overconsolidated and the clay was overconsolidated. Moreover, the coefficient of permeability was small and the rate of settlement consolidation was slow. The results revealed that the site engineering conditions were evaluated more accurately by the multi-function CPTU test technology.

Investigation of the effect of soil matrix on flow characteristics for soil and rock mixture

The flow characteristic is important to soil and rock mixture (SRM). Seepage of SRM includes a combination interaction between soil matrix, rock blocks and rock–soil interfaces. Properties of soil matrix play crucial role in controlling the flow rule of SRM, yet the effects of different kinds of soil matrix in SRM on its flow mechanism are still poorly understood. In this work, the authors present the results of a state-of-the-art investigation on the flow properties of SRM with clay, mucky soil and fine sand matrix. A self-developed servo-controlled large-scale permeability testing system was used to carry out the flow test. From the test results, the flow rules are different for SRM with different kinds of soil matrix. For a matrix composition of clay and mucky soil, the flow law follows the non-Darcy law; however, it follows Darcy's law for the SRM with a fine sand matrix. The non-Darcy flow properties are studied with the Forchheimer equation to obtain the permeability coefficient for SRM with different rock block percentages.

Study on relationship between static cone penetration strength and shear strength of soil

On basis of the analysis on results of laboratory test, the field vane shear test and the static cone penetration test of different types of soil in Tianjin, it is proposed that there is significant positive linear correlation between the static cone penetration tip resistance and the vane shear strength. Moreover, for clay a more distinct linear correlation exists than that for mucky soil and silty clay. Therefore the results of static cone penetration test can be applied to the stability calculation.

Actinoplanes lutulentus sp. nov., isolated from mucky soil in China

A novel actinomycete, designated strain NEAU-GRX6T, was isolated from mucky soil collected from a stream of Jinlong Mountain in Harbin, Heilongjiang Province, north China, and characterized using a polyphasic approach. The isolate formed irregular sporangia containing motile sporangiospores on the substrate mycelium. The whole-cell sugars were xylose, glucose and galactose. The predominant menaquinones were MK-9(H6), MK-10(H4) and MK-9(H4). The major fatty acids were C16:0, C15:0, C18:1ω9c, C17:1ω7c and C18:0. The phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol. The DNA G+C content was 67 mol%. 16S rRNA gene sequence similarity studies showed that strain NEAU-GRX6T belonged to the genus Actinoplanes, being most closely related to Actinoplanes palleronii IFO 14916T (97.80% similarity) and Actinoplanes missouriensis NBRC 102363T (97.76%). However, the low observed levels of DNA-DNA relatedness allowed the isolate to be differentiated from the above-mentioned species of the genus Actinoplanes. Moreover, strain NEAU-GRX6T could also be distinguished from A. palleronii IFO 14916T and A. missouriensis NBRC 102363T by phenotypic characteristics. Therefore, it is proposed that strain NEAU-GRX6T represents a novel species of the genus Actinoplanes, for which the name Actinoplanes lutulentus sp. nov. is proposed. The type strain is strain NEAU-GRX6T (=CGMCC 4.7090T=DSM 45883T).