Cement-soil Pile Research Articles

The Application of Sheet Steel Piles Combined with Soil-Cement Piles to Stabilize a Deep Excavation Pit’s Wall

In recent years, owing to advances in technology, excavation pits have shown increased improvements. Taking advantage of advanced solutions combined with traditional ones has brought about considerable advantages for construction contractors and saves on expenses to carry out construction projects. Owing to their ability to analyze geotechnical problems, several calculation and simulation software, such as Plaxis, Bentley, along with many others, have grown in popularity. Among them, Midas is one such software, which is a set of solutions developed by the MIDAS IT company and is widely applied in many constructions. The authors evaluated the ability to use Midas software to calculate the stability of a wall in a deep excavation pit for the Ho Chi Minh City Water Environment Improvement Project. The results of these researches reveal that combining soil-cement piles and sheet steel piles decreases the internal forces in sheet steel pile walls. At the same time, this solution not only reduces horizontal displacement but also keeps the settlement of the soil around the excavation pit within the permissible range, which helps to ensure that the adjacent pavements are stable and will not crack. The results of this study can be applied to similar geological constructions.

夯实水泥土桩复合地基主要性状研究

夯实水泥土桩复合地基主要性状研究

An integrated way to improve the properties of soil-cement pile foundations

The scientific article presents the results of the development of a method for improving the properties of soil-cement pile foundations by the drilling-mixing method using mechanical activation of soil-cement mixture in filler soils. Two methods for improving filler soils are considered. The choice of the mathematical methods for the research is justified. The feasibility of a complex combination of mathematical modeling methods and experimental design to achieve the goal set in this scientific article is substantiated. The physicomechanical characteristics of soil-cement are considered: a measure of brittleness, brittleness coefficient, compressive strength, splitting strength, strength variation coefficient. Based on the research, practical recommendations are given for improving soil-cement pile foundations.

Strengthening of soil and foundations of construction objects in order to reduce operating costs

This article discusses the method of strengthening the slab foundation, carried out by summing up the soil-cement piles. Piles should be located under the loaded structures of the capital construction object – walls and pillars. Based on the results obtained in the study, it was found that with a reduction in the effective loads of up to 46 % in the soil-cement piles, the stiffness of these piles increases by 10–12 %, and the bending moments in the base plate decrease by 0.5–3 %. The load on the pile gain becomes uniform with a uniform structure of the building in the plan. The difference between the limit and average values reaches 14 %. Based on the obtained numerical data, the authors produced a method for calculating the load on the soil-cement piles while strengthening the slab foundation, including the loads transferred to the base of the slab prior to the reinforcement process. A technique for designing the foundation pile foundation was also developed. This technology allows to reduce the load on the piles by more than 2 times according to the obtained calculations, also reduce the cost of work to strengthen the slab foundation and material consumption by up to 30 %. The authors on the basis of the study made the following conclusions: knowledge of the origin of soils, the conditions of their creation and changes in the course of the subsequent existence of their composition and structure allows us to influence their physico-mechanical properties. This will make it possible to correctly assess the reliability and their deformability throughout the entire construction of facilities and at the stage of their operation, therefore, will allow to reduce operating costs.

COMPARATIVE CALCULATION OF THE STABILITY OF THE LANDSLIDE SLOPE IN THE SOFTWARE COMPLEXES «OTKOS» AND «LIRA-CAD 2017»

Purpose. The analysis and comparison of the results of calculation by the finite-element model of the slope in the software complex «LIRA-CAD 2017» with the determination of the its stability in the software complex «OTKOS» allows to determine the accuracy the results and the most favorable conditions for the development of the displacement and parameters of the most dangerous surface slip for further calculation of anti-slip retaining structures. Methodology. The geomorphological data were obtained from the results of laboratory studies of soils in the considered slope. Creation of a bulk finite element model of the slope in accordance with the built cuts and depths of soil layers. Calculation of the nonlinear problem of finite-element simulation of the slope in the software complex «LIRA-CAD 2017». Creation and calculation of the stability problem of the landslide slope in the software complex «OTKOS» and comparison of the results of the its stress-strain state. Results. The results of calculating the finite-element model of the landslide slope in the software complex «LIRA-CAD 2017» and its stability in the software complex «OTKOS» were obtained. The analysis of the obtained results of sliding surfaces study is carried out. The calculation of the strengthening of the slope area is carried out with the help of soil cement retaining piles, located at right angles to the vector of the displacement direction. Originality. Despite the presence of a large number of different methods of studying the surfaces of sliding, it is impossible to determine exactly the scenario of the displacement, using only one of the calculation methods. First of all, this is due to the rather high variation of the initial data of the problem, which in turn depends on the environment and assumptions, as well as on external factors that can not be taken into account precisely. The next task is to carry out the calculation of the strengthening of the landslide slope by soil-cement piles. Practical value. It is known that it is advisable to use soil-cement piles as a protective element, which interacts well with the soil environment due to its structure of the source material. A comparative analysis of the calculation results of the slope stability with the help of software systems «LIRA-CAD 2017» and «OTKOS» gives an answer to the question of the its reliability.

ЗАБЕЗПЕЧЕННЯ НАДІЙНОЇ ЕКСПЛУАТАЦІЇ НАФТОВИХ РЕЗЕРВУАРІВ У СКЛАДНИХ ГЕОТЕХНІЧНИХ УМОВАХ ПРИ СЕЙСМІЧНИХ ВПЛИВАХ

ЗАБЕЗПЕЧЕННЯ НАДІЙНОЇ ЕКСПЛУАТАЦІЇ НАФТОВИХ РЕЗЕРВУАРІВ У СКЛАДНИХ ГЕОТЕХНІЧНИХ УМОВАХ ПРИ СЕЙСМІЧНИХ ВПЛИВАХ

Economic efficiency of vibroreinforced soil-cement piles implemented in construction

The results of the executed economic comparison of foil-cement piles reinforcement use by vibroreinforced - vibroreinforced soil-cement piles are presented. The comparison is based on the results of piles bearing capacity by field tests. Considering the results of field tests two variants of piles foundation have been designed for residential building. Economical comparison is made for implementation effectiveness of reinforced and non-reinforced soil-cement piles at the piles calculated bearing capacity on the soil that is greater than the calculated bearing capacity by the material. .Economical comparison is made for implementation effectiveness of vibrated vibroreinforced soil-cement piles and bored piles at their calculated bearing capacity by the material at times greater than that on the soil. The obtained results and the determined economic effect are analyzed. The results of comparison are used for design and implemented in construction.

Performance of Cement–Soil Pile Composite Foundation with Lateral Constraint

A lateral constraint can effectively reduce the foundation settlement and reduce the stress of a pile shaft in a foundation treatment. Based on the characteristics of railway engineering and soft soil engineering, this paper studied the influence that lateral constraint exerted on the stress and settlement of cement–soil pile composite foundation by using indoor large-scale model testing. A comparative analysis of the stress and settlement of cement–soil pile and soil following load change is performed, and the mechanism of lateral constraint is discussed. The results show that the settlement of the pile top with lateral constraint is 8–30% lower and that of the soil around the pile is 7–9% lower when comparing the settlement values of the composite foundation with and without lateral constraint in the cement–soil pile composite foundation. The stress value of the pile top in the composite foundation with the lateral constraint is 18–32% lower than that without any lateral constraint. The stress of the cement–soil pile shaft first increases and then decreases with the depth, and the maximum stress appears at 0.15–0.35 times the pile length from the top. The position of the maximum axial force of the pile without a lateral constraint is lower than that with a lateral constraint, and the maximum stress value of the pile is 112–153% of the stress value of the pile top. Therefore, setting the lateral constraint can effectively stop the lateral deformations of soft soil, reducing the settlement of the composite foundation and pile shaft stress.

Vibrated Soilcement Piles

The article describes the vibration research effect of on strength increasing and soilcement density. Laboratory studies of vibration impact on soilcement during manufacturing on the basis of loam and sandy soils have been performed. The field experimental determination of deep high-frequency vibration influence on soilcement piles material characteristics has been fulfilled. The process of material shrinkage during manufacture has been investigated. The obtained results are introduced in the process of soilcement base and foundations placement. Field comparative tests with static compressive loading of three types of piles, including vibro-compacted soilcement piles, have been conducted. With the PLAXIS software system, and with it’s axisymmetric particular version, the relationship between loading and soilcement piles settling was established. Numerical stamp tests modeling with the help of the software system PLAXIS was performed to detect the soilcement vibration influence on the reinforced base deformation.

Investigation of Performance of Soil-Cement Pile in Support of Foundation Systems for High-Rise Buildings

This paper presents the experimental study of Soil-Cement Pile (SCpile) by wet mixing method in sandy soils, with the typical project at An Trung Complex apartment, Da Nang city, Vietnam. With the characteristic of soil layers is sandy soil, the strength of laboratory stabilized soils with the amount of cement from 150¸300 kg/m3 was determined. Simultaneously, the authors also performed the experiments of 20 test piles collected from the site which has cement content about 280 kg/m3 and the unconfined compressive strength qu= (4.5-6.0) MPa. After that, a full-scale model static axial compressive load tests of two single piles and a group of four piles with diameter 800 mm and 12 m length were also conducted. The experiment results show that the bearing capacity of every single pile is 1.200 kN with settlement 6.93 mm and the group of four CSpiles is 3.200 kN with settlement 5.03 mm. The results presented in the paper illustrate that SCpile is the suitable solution for foundation construction process with low cost and saving time for high rise buildings. The result shows a capable application of soil cement piles for support of high-rise buildings.

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.

Nonlinear Stress Analysis of Flexible Pile Composite Foundation by Energy Method

To calculate the stress of cement‐soil pile (flexible pile) in composite foundation accurately and overcome the defective preposition that the pile and the soil are elastic, the nonlinear analysis and calculation of pile‐soil stress by adopting the energy method are performed. First, on the basis of the universally adopted load transfer method, it is assumed that the friction and the relative displacement of the pile shaft conform with the elastic‐plastic relationship. Then, the modified Cam‐clay model is introduced to calculate the compressive amount of soil around the pile. Further, the stress and strain characteristics curve of the flexible pile is used to calculate the compression of the pile, deducing the energy equation of the pile and soil around the pile, establishing the total potential energy expression of the flexible pile composite foundation, and the load sharing value and the corresponding stress value of the pile‐soil are obtained based on the minimum potential energy principle. Finally, this method is verified by indoor laboratory model test and the reported case. The results show that the calculated solutions are in agreement with the measurements; therefore, the calculation method is reasonable.

STUDY OF THE EFFECT OF SOIL CEMENT ELEMENTS WHEN STABILIZING ROADBED MODEL IN LABORATORY CONDITIONS

Purpose.Experimental studies allow determining th estress-strain state or bearing capacity of the tested soil body. A preliminary study of the results of model testing and experimental research allows us to find the optimal solutions and to justify the parameters of the chosen technology. The purpose of this work is to determine the effect of soil cement elements when stabilizing the roadbed on a weak subgrade using the soil tests in laboratory conditions. Methodology. During the development of measures for the reconstruction and consolidation of soil bodies, their strength is tested using many methods. In all cases, we take into account the physical and mechanical characteristics of soils obtained as a result of research, as well as the existing regulatory documents. We performed the experimental studies by model testing in laboratory conditions. The model testing was based on the corresponding relationships between geometric sizes, mechanical properties of materials, loads and other factors on which the stress-strain state depends. During testing, the model was loaded gradually. We maintained each load level up to conditional stabilization of the soil deformation. We took the readings from measuring devices at each stage of loading after achievement of stabilization of soil mass deformations. We fixed the readings in the test journal. Findings. During stabilization with soil cement piles there is an improvement in mechanical properties, which leads to a decrease in deformations by 2…3.5 times. Each test is accompanied with graphs of relative deformations-stress dependence, as well as deformation curves and compression curves. According to the results of experimental stu-dies, it can be seen that when testing a model with cement piles, compared with a model without soil cement piles, the relative deformations of the samples taken prior to the experiment and after the experiment almost coincide, indicating a decrease in deformability under load. Originality. We proved that this stabilization type positively affects the stress-strain state of the soil body, by increasing its physical and mechanical characteristics. The obtained results allow for rational design of subgrade stabilization work with the help of modern technologies.Practicalvalue. The in-depth analysis of the results of experimental studies opens up possibilities for theoretical synthesis and development of theoretical foundations, which will allow in the future avoiding, in the similar cases, the experimental verification of the stabilization type given for the relative type of soil. It is confirmed that this method of stabilization used can be applied in real conditions.

INTERACTION OF SOIL-CEMENT PILE SUPPORTING STRUCTURES WITH THE BODY OF A LANDSLIDE

Purpose. Analysis and comparison of the landslide slope finite element model calculation results of the appliance of soil-cement piles, depending on the variation of the retaining structure rigidity, makes it possible to evaluate the effectiveness of their application and the cooperative work of piles with the displacement body. It also makes it possible to make a conclusion about the advantages of using this anti-landslide protection method of the slope. Methodology. Analysis of geomorphological data obtained from the results of laboratory studies of soils on the slope section is considered. Creation of a three-dimensional finite-element slope model according to the constructed sections and depths of the soil layers. Calculation of the nonlinear problem of finite element modeling of the slope with applying of soil-cement piles of various rigidity. Findings. The obtained results of calculating the finite element model of the landslide slope, and the analysis of the stress-strain state of the construction with soil-cement piles has been carried out. Originality. Despite the widespread of using soil-cement piles as enclosing structures for the construction of foundation pits and reinforcement of foundations of emergency structures, special attention should be paid to the study of the expediency of using soil-cement retaining pile structures on landslide areas. Practical value. It is known that soil-cement retaining piles are expediently in use as a protective element, which interacts quite well with the ground environment due to its structure of the initial material. Using of modern computer programs of finite element modeling makes it possible to calculate the efficiency of the use of soil-cement piles and to determine the parameters of the necessary retaining structure according to the given geological structure of the slope, and also, depending on its shape and the physical characteristics of the soils, to compare the performance of different protective landslide structures types.

РАСЧЕТ И ПРОЕКТИРОВАНИЕ УСИЛЕНИЯ ПЛИТНОГО ФУНДАМЕНТА ГРУНТОЦЕМЕНТНЫМИ СВАЯМИ

РАСЧЕТ И ПРОЕКТИРОВАНИЕ УСИЛЕНИЯ ПЛИТНОГО ФУНДАМЕНТА ГРУНТОЦЕМЕНТНЫМИ СВАЯМИ

Seismic response of a continuous foundation structure supported on partially improved foundation soil

The response of a continuous foundation structure supported on partially improved foundation soil was recorded during an earthquake. The measured results show that partially improved foundation soil can induce torsional response of the foundation due to the irregular soil-foundation system. A numerical model considering soil-structure interaction was then established, and the numerical results were compared with the observation data. Using the validated numerical model a parametric study was carried out to investigate the torsional response of a continuous foundation structure with irregular soil foundation system. It can be concluded from the study that eccentricities in the soil foundation system would result in a torsional response. Particularly with different lengths of soil-cement piles in the partially improved foundation soil, the generated torsional response can not be ignored during the seismic excitation.

PRELIMINARY STUDY OF SOIL-CEMENT PILING AS A NEW ALTERNATIVE IN LEVEE AND RIVER BANK STRENGTHENING

Malaysiahas not yet experienced a totally severe levee failure as what have happened in other countries. However, flood has always been the major problem inMalaysiacaused by several factors including weather condition, man-made and also including levee or bund failure. Therefore, in order to produce a new alternative to improve the structures of levees and river banks, this study on preliminary investigation of soil-cement piling is done to see the possibility of it to be used in the strengthening of levee or bund and river banks. The investigation focused on determining suitable soil-cement ratio to produce soil cement pile encased in PVC pipes in terms of axial capacity. The results show that the soil-cement mixture with 11% cement ratio produced the reasonable pile axial/compressive capacity.

A simplified method for impedance and foundation input motion of a foundation supported by pile groups and its application

A simplified method is developed to analyze the impedance and foundation input motion of foundations supported by pile groups. In the proposed method, neighboring piles are replaced by a single equivalent pile. This replacement process reduces the number of degrees of freedom as well as the required computer memory and calculation time. To validate the simplified method, the impedance and foundation input motion of a raft foundation and an embedded foundation supported by pile groups with rigid and pin-jointed conditions between the pile head and foundation are calculated using both a simplified method and a rigorous numerical method. The results show that the proposed simplified method for the impedance and foundation input motion analysis of a foundation with a large number of piles yields sufficient accuracy. The simplified method is also applied to estimate the dynamic response of an isolated structure with a foundation supported by 2203 cement–soil piles with consideration of the soil–structure interaction. The results show that the dynamic response of the structure can be precisely simulated using the simplified method.

MODERN METHODS OF REINFORCEMENT OF WEAK FOUNDATIONS OF ROADS

The article discusses the method of reinforcing weak foundations of automobile roads in the Urals that uses soilcement piles produced through jet grouting. The article demonstrates that armed ground pile foundations lead to substantial increase of the bearing capacity of the foundation, however the effectiveness of the method largely depends on the thickness and the lithologic composition of the foundation soils.

Soil-cement piles by drilling-mixing method

Soil-cement piles by drilling-mixing method