scholarly journals An Experimental Study on the Reinforcement of Silt with Permeable Polyurethane by Penetration Grouting

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Chaojie Wang ◽  
Qi Liu ◽  
Chengchao Guo ◽  
Yangyang Xia ◽  
Yanjie Hao ◽  
...  
Keyword(s):  
Soil Structure ◽  
Coupling Effect ◽  
Interaction Mechanism ◽  
Engineering Practice ◽  
Grouting Pressure ◽  
Grouting Material ◽  
Jet Grouting ◽  
Diffusion Pattern ◽  
Diffusion Speed ◽  
Penetration Grouting

To meet the demand of antiseepage and reinforcement of soil dams, a kind of permeable polyurethane grouting material was developed. A visual steady-pressure grouting test device was designed to study the law of polyurethane diffusion and reinforcement in silt under different pressure, and the interaction mechanism of grout and soil body structure was explored microscopically. The results showed that, with the increase in the grouting pressure, the diffusion speed rose, and the diffusion pattern of grout in the soil also changed from permeation diffusion to permeation splitting. Under the effect of grouting pressure, more tiny cracks will occur in the soil structure, leading to the use of more grout, thus increasing the strength of the consolidated soil by more than 10 times. The results of SEM-EDS and mercury intrusion test proved that the polyurethane had a significant filling effect on the soil structure, which could effectively reduce the porosity of the soil and cement the soil particles through wrapping, complexing, and hydrogen bonding, thereby improving the soil properties. Moreover, the results revealed from a microscopic perspective that the grouting altered the pore structure of the soil structure through the seepage-erosion-splitting coupling effect, but when the grouting pressure exceeded 0.4 MPa, the soil particle and grout would be partially remixed and arranged closely, showing a phenomenon of jet grouting. Finally, the material was used in engineering practice, achieving a satisfactory grouting treatment effect.

scholarly journals Development of Modified Grouting Material and Its Application in Roadway Repair Engineering

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yang Yu ◽  
Zhengyuan Qin ◽  
Xiangyu Wang ◽  
Lianying Zhang ◽  
Dingchao Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Mass Ratio ◽  
Control Effect ◽  
Grouting Pressure ◽  
Grouting Material ◽  
Wide Range ◽  
Grouting Reinforcement ◽  
Grouting Materials

It is very extraordinary for the success of coal mine roadway grouting with the following factors of high early strength, good fluidity, and convenient pumping, but the existing grouting materials make it difficult to achieve the above characteristics at the same time. Therefore, a modified grouting material is developed, which is composed of two kinds of dry materials A and B, which are mixed with water and in equal amounts. The physical and mechanical properties of modified grouting materials under different ratios were tested by laboratory orthogonal test, and the optimal ratio of grouting materials and additives was obtained: (1) the water-cement ratio is 0.8 : 1; (2) base material: the mass ratio of cement, fly ash, bentonite, and water is 1 : 0.3 : 0.1 : 1.44; (3) admixture: the mass ratio of water reducer C, accelerator D, and retarder E is 1.5% : 0.05% : 0.3%. The basic properties of the modified grouting materials were studied from the aspects of slurry flow state, diffusion range, and grouting parameters by using the numerical simulation method, and the reinforcement mechanism of slurry to the broken surrounding rock properties of the roadway was revealed: (1) the grouting pressure is the main factor affecting the slurry diffusion radius; (2) the mechanical properties of the roadway surrounding rock are improved, the plastic zone and deformation of surrounding rock are reduced, and the active support function of the anchor and cable is enhanced through grouting reinforcement; (3) the control effect of the roadway is improved, and the balanced bearing with anchorage structure of the roadway surrounding rock is realized through grouting reinforcement. On this basis, the modified grouting material is applied to roadway repair and reinforcement engineering practice. The field monitoring data show that the production practices were guided by roadway repair and reinforcement technology with the modified grouting material, as the core of the roadway surrounding rock control effect is good, and the modified grouting material has a wide range of application prospects.

scholarly journals Mechanical Characteristics of Cement-Based Grouting Material in High-Geothermal Tunnel

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1572 ◽  
Author(s):  
Mingnian Wang ◽  
Yunpeng Hu ◽  
Cheng Jiang ◽  
Yicheng Wang ◽  
Dagang Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Relative Humidity ◽  
Mechanical Characteristics ◽  
Coupling Effect ◽  
Peak Stress ◽  
Curing Temperature ◽  
Peak Strain ◽  
Humidity Effect ◽  
Grouting Material ◽  
Study Results

The cement-based grouting materials used for practical purposes in high-geothermal tunnels are inevitably affected by humidity and high temperature, leading to the deterioration of mechanical properties. Based on the characteristics of changing high temperatures and two typical conditions of hot-humid and hot-dry environments in high-geothermal tunnels, many mechanical strength tests were carried out on the grouting material cured under different environmental conditions. The study results indicated that high temperature and low relative humidity were unfavorable to the development of mechanical characteristics of grouting material, but the coupling effect of two factors could improve the strength at early ages and reduce the degradation of long-term strength. As the curing temperature exceeded 56.3 °C, the humidity effect on strength played a more important role in recovering the strength of grouting material damaged by high temperature. Temperature had more significant impact on the relative peak stress while the relative humidity had greater influence on the relative peak strain. A calculation compressive constitutive model was prospered, which considering both temperature and relative humidity. The study results may provide much valuable experimental data and theoretical supporting for the design of compression constitutive of cement-based grouting material in high-geothermal tunnel.

Analysis on Segment Floating in the Construction of Large-Diameter Crossing-River Shield Tunnel

2015 ◽  
Vol 724 ◽  
pp. 17-21
Author(s):  
Run Lai Zhang ◽  
Li Ming Tang ◽  
Kun Tang
Keyword(s):  
Frictional Force ◽  
Large Diameter ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Factors Affecting ◽  
Grouting Pressure ◽  
Rapid Setting ◽  
Grouting Material ◽  
Longitudinal Stiffness ◽  
Initial Solidification

Segment floating is a common problem met in the construction of large-diameter crossing-river shield tunnel. The factors affecting segment floating are discussed first and analyzed by numerical simulation, including the properties of grouting material, the speed of shield tunneling, grouting pressure difference, the tunnel longitudinal stiffness, frictional force between segment rings and weight of the supporting system. The simulation results indicate that segment floating will reduce by shortening slurry’s initial solidification time, slowing shielding speed, improving the tunnel longitudinal stiffness as well as increasing the frictional force between segment rings. And some measures are given such as applying new rapid-setting slurries, shear pins, rubber mats with high friction coefficient and pre-stressed bolts

Mechanical Performance of Geosynthetic-Reinforced Pile-Supported Embankments

2010 ◽  
Vol 156-157 ◽  
pp. 1696-1701
Author(s):  
Ling Sun ◽  
Jun Jie Zheng ◽  
Jun Zhang ◽  
Qiang Ma
Keyword(s):  
Mechanical Performance ◽  
Soft Soil ◽  
Interaction Mechanism ◽  
Measured Data ◽  
Engineering Practice ◽  
Circular Arc ◽  
Arching Effect ◽  
Pile Cap ◽  
Current Design ◽  
Embankment Load

According to the characteristics of the soft soil subgrade reinforced by geosynthetic and piles, the deformation of geosynthetic was modeled as circular arc and the arching effect in embankments and the interaction of piles and soil are both considered in the calculation. The interaction mechanism of geosynthetic, pile and soil under the embankment load was analyzed. The method presented in this paper was validated by comparing with the testing results and three current design methods in the literature. The results show that the analytical solutions have agreement with the measured data and can be applied in engineering practice. Finally, four important parameter (the differential settlement, the diameter of pile, the width of pile cap, the height of equal settlement plane) were investigated.

scholarly journals A comparative study of soil-structure interaction in the case of frame structures with raft foundation

2016 ◽  
Vol 63 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Balázs Móczár ◽  
Zsuzsanna Polgár ◽  
András Mahler
Keyword(s):  
Elastic Foundation ◽  
Soil Structure ◽  
Structural Engineering ◽  
Soil Structure Interaction ◽  
Engineering Practice ◽  
Subgrade Reaction ◽  
Element Analysis ◽  
Structure Interaction ◽  
Beam On Elastic Foundation ◽  
Raft Foundations

AbstractDesign and modelling of raft foundations and selecting the value of coefficient of vertical subgrade reaction are still actively discussed topics in geotechnical and structural engineering. In everyday practice, soil–structure interaction is mostly taken into account by using the theory of ‘beam on elastic foundation’, in which the soil is substituted by a certain set of coefficients of subgrade reaction. In this study, finite element analysis of a building was performed using a geotechnical software (Plaxis 3D), which is capable of modelling the subsoil as a continuum, and a structural software (Axis VM), which uses the concept of ‘beam on elastic foundation’. The evaluation of the results and recommendations for everyday engineering practice are introduced in this paper.

On the Soil-Structure Interaction Numerical Study of Strengthening Design of Sluice within Mining Subsidence Areas

2010 ◽  
Vol 163-167 ◽  
pp. 3640-3644
Author(s):  
Hong Chang ◽  
Jun Wu Xia ◽  
Hong Fei Chang ◽  
Feng Jie Zhang
Keyword(s):  
High Pressure ◽  
Pile Foundation ◽  
Soil Structure ◽  
Numerical Study ◽  
Mining Subsidence ◽  
Soil Structure Interaction ◽  
Analysis Model ◽  
Structure Interaction ◽  
Jet Grouting ◽  
The Stability

Finite element models, established using ANSYS, given the soil - structure interaction phenomena produced at the interface between the reinforced concrete structure and the soil, have been used to perform a parametric study of the strengthening design of the foundation and the sluice chamber within mining subsidence area. High pressure jet grouting pile is adopted to reinforce the foundation, this analysis model is simplified by the transformation from the pile foundation to the solid foundation, which reflects the characteristic of pile foundation. The strengthening design of the sluice chamber is a renovation from open style to frame, to increase the integral property. It is indicated that, using high pressure jet grouting pile to reinforce the foundation can apparently improve the stability of sluice in mining area. Nevertheless, it can't improve the stability of sluice through reinforcing the sluice chamber.

Analysis of Anti-Floating Measures and Construction Parameters of Shield Tunnel through River under Ultra-Shallow Covering

2013 ◽  
Vol 353-356 ◽  
pp. 628-634
Author(s):  
Xiao Long Li ◽  
Bing Long Wang ◽  
Xue Li ◽  
Chang Ji
Keyword(s):  
Construction Safety ◽  
Chamber Pressure ◽  
Shield Tunnel ◽  
Floating Plate ◽  
Surface Uplift ◽  
Grouting Pressure ◽  
Driving Speed ◽  
Jet Grouting ◽  
Uplift Pile

Shield tunnel through the river under shallow covering usually facing the phenomenon of tunnel floating due to the thickness of overburden layer inadequate,and resulting in flooding accident due to the overburden layer split.Aiming at the project of Hangzhou metro line one through the Tangjia river under ultra-shallow covering,checking the thickness of overburden layer and taking the measures of anti-floating plate,uplift pile and jet-grouting piles to resist tunnel floating;through the control of soil chamber pressure,driving speed and grouting pressure in the process of construction,tunnel axis is controlled within±30mm,the amount of surface uplift is less than 10mm,tunnel segments without breakage and leakage.The results show that using anti-floating plate,uplift pile and jet-grouting piles,and controlling the construction parameters strictly are effective measures to resist tunnel floating and ensure construction safety.

scholarly journals Numerical analysis of reducing tunneling effect on viaduct piles foundation by jet grouted wall

2021 ◽  
Vol 15 (1) ◽  
pp. 75-86
Author(s):  
Kamel Asker ◽  
Mohmed Tarek Fouad ◽  
Mohamed Bahr ◽  
Ahmed El-Attar
Keyword(s):  
Numerical Model ◽  
Interaction Mechanism ◽  
Back Analysis ◽  
Bending Moment ◽  
Pile Group ◽  
Tunneling Effect ◽  
Shield Tunnel ◽  
Pile Groups ◽  
Perfectly Plastic ◽  
Jet Grouting

Purpose. The target of this study is divided into two parts. The first part is concerned with capability of numerical model to simulate the tunneling process. The second part is related to studying the interaction mechanism between the tunnel, protection technique, and soil. This study themes are investigated by analyzing different protection technique configuration, considering different stiffness of the grouted wall, and applying different interface coefficient between the wall and the soil. Methods. The method used in this study to check the accuracy of the proposed numerical model is 4-D ABAQUS program. The typical excavation of a tunnel is simulated step by step with an assumed rate of tunnel advancement (0.5 to 1.5 m/hr). The soil material utilized in this model is elastic perfectly plastic (the Mohr-Сoulomb criterion), while elastic material is modeled as solid element (S4R) adopted for lining, grouting, filling gaps, shielding, constructing piles, and jet grouted wall. Findings. Results showed that the closer jet grouting to the tunnel with embedded length of 1.5 times tunnel diameter, the better effect on reducing the lateral deformation and bending moment generated on piles. Otherwise, increasing wall thickness more than double grouted column diameter would not affect its shielding efficiency. Furthermore, either increasing or decreasing friction coefficient even if rough between the grouted wall and soil had no effect on the pile behavior. Additionally, applying Mohr-Coulomb criteria for grouted wall with high stiffness allowed realistic response of the pile group. Originality.Capability of the proposed model is verified by back analysis of Changsha Subway Line 1 project, where the shield tunnel would be constructed near existing pile groups of L off-ramp of the Xinzhong Road viaduct. Practical implications. Increasing grouted wall configuration is more effective than mechanical properties or its interface coefficient with surrounded soil in mitigating tunneling effect on nearby piles. Keywords: tunneling, jet grouting, gield measurements, ABAQUS, Changsha Subway Line 1

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