scholarly journals Study on Grouted Body Deterioration Mechanism of Sand Layer in Seawater Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Hongbo Wang ◽  
Zhipeng Li ◽  
Xiaoguo Wang ◽  
Qingsong Zhang ◽  
Lianzhen Zhang
Keyword(s):  
Marine Environment ◽  
Physical And Mechanical Properties ◽  
Quantitative Relationship ◽  
Sand Layer ◽  
Underground Engineering ◽  
Significant Deterioration ◽  
Degradation Ratio ◽  
Deterioration Mechanism ◽  
Seawater Environment ◽  
Grouting Reinforcement

Water-rich sand is a common stratum in marine underground engineering. Grouting is the most common method for solving geological disasters in water-rich sand. However, the marine environment differs greatly from the land environment. The erosion and seepage of seawater ion cause significant deterioration of grouted body, which reduces the physical and mechanical properties of grouted body. The maintenance of grouted body performance is the guarantee of long-term safe operation of the tunnel in the marine environment. In order to solve the problem of long-life grouting design for sand layer in seawater environment, an accelerated test of grouted body erosion under seawater erosion environment is designed to study the mesomorphological characteristics of seawater erosion on grouted body erosion and to reveal the mechanism of seawater erosion and solids. The evolution law of grouting plus solid strength under different slurry water-cement ratios and different seawater erosion time conditions is analyzed. The results show that the grouting plus solid effective time for water-cement ratios of 0.8 : 1, 1 : 1, 1.4 : 1, and 2 : 1 is 75a, 60a, 30a, and 15a; the index of strength degradation ratio of seawater environment to grouting plus solids is proposed, and the quantitative relationship between seawater erosion time and grouting plus solids strength is established, which provides theoretical basis for sand layer grouting reinforcement in seawater environment. We hope to provide some reference for the design and construction of sand grouting in seawater environment.

scholarly journals Damage Model and Experimental Study of a Sand Grouting-Reinforced Body in a Seawater Environment

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2495
Author(s):  
Hongbo Wang ◽  
Quanwei Liu ◽  
Shangqu Sun ◽  
Qingsong Zhang ◽  
Zhipeng Li ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Underground Structure ◽  
Damage Model ◽  
Strain Curve ◽  
Sand Layer ◽  
Stress Strain Curve ◽  
Underground Engineering ◽  
Stress Strain ◽  
Seawater Environment

A water-rich sand layer is a common stratum in marine underground engineering. Grouting is a technology for soil or rock sealing, a method to solve the water seepage problem, and can be used to solve geological challenges in water-rich sand layers. A grouting-reinforced body deteriorates by the long-term erosion of seawater, resulting in attenuation of the performance of the solid. Obtaining the decay law of the performance of the grouting-reinforced body can guarantee the safe operation of the underground structure over a long life cycle. To this end, by describing the solid damage after seawater erosion, the stress–strain curve and the relationship between the damage variable and the internal micro-cracks and pores in the grouting-reinforced body were analyzed. Then, a constitutive model of the solid damage in the seawater environment was established. The stress–strain curve of added solid after deterioration was obtained by designing an indoor grouting reinforcement test and an accelerated deterioration test. Finally, the constitutive model of the sand layer plus solid deterioration in a seawater environment was determined. This research is of great importance for improving the deterioration theory under a seawater environment and ensuring the long term safety of tunnel operations.

scholarly journals Effect analysis of grouting reinforcement ring considering fluid solid coupling

2019 ◽  
Vol 277 ◽  
pp. 03014
Author(s):  
Heng Zhou ◽  
Xiaochen Wang ◽  
Haojie Liu ◽  
Yanan Liu ◽  
Chenyang Ma ◽  
...  
Keyword(s):  
Surrounding Rock ◽  
Physical Parameters ◽  
Sand Layer ◽  
Effect Analysis ◽  
Reinforcement Ring ◽  
Before And After ◽  
Grouting Reinforcement ◽  
Set Up ◽  
Subway Tunnels ◽  
The Relationship

Geological hazards such as instability of surrounding rock and leakage of water are easily occurred in subway tunnels crossing water rich sand layers. Based on the principle of fluid solid coupling in porous media, this paper studies the plastic zone distribution of surrounding rock and reinforcement ring, vertical settlement of tunnel vault and water seepage of tunnel before and after grouting reinforcement for water rich sand layer. Considering the compressibility of rock mass, the relationship between porosity, permeability and volume strain is further deduced and simplified. A set of numerical calculation formula is set up to study the change of physical parameters of the water rich sand layer before and after grouting to determine the grouting effect and select the thickness of the best grouting reinforcement ring. The results show that the deformation and water permeability of the tunnel decrease with the increase of the thickness of the grouting reinforcement ring. The thickness of the grouting reinforcement ring is the most reasonable when the thickness of the reinforcing ring reaches a certain value, and the thickness of the grouting reinforcement ring is designed to be 5~6m. The research results have been successfully applied in the grouting project of Qingdao Metro stone elderly bathing beach. The reliability of the numerical simulation is verified by comparing the data from the field monitoring and measurement, providing reference for the related projects.

scholarly journals Experimental Study on the Reinforcement Mechanism of Segmented Split Grouting in a Soft Filling Medium

Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 131 ◽  
Author(s):  
Zhipeng Li ◽  
Shucai Li ◽  
Haojie Liu ◽  
Qingsong Zhang ◽  
Yanan Liu
Keyword(s):  
Elastic Modulus ◽  
Permeability Coefficient ◽  
Three Dimensional ◽  
Weighted Average ◽  
Quantitative Relationship ◽  
Uniaxial Compression Test ◽  
Distribution Characteristics ◽  
Reinforcement Mechanism ◽  
Before And After ◽  
Grouting Reinforcement

Subsection split grouting technology can effectively improve the grouting efficiency and homogeneity of grouting in a target reinforcement area. It is therefore necessary to clarify the reinforcement mechanism and characteristics of the soft filling medium under the condition of split grouting. A three-dimensional grouting simulation test of segmented split grouting in a soft filling medium was conducted. The distribution characteristics and thicknesses of the grouting veins were obtained under the condition of segmented grouting. The mechanical mechanism of segmented split grouting reinforcement, based on the distribution characteristics of different grouting veins, was revealed. After grouting, a uniaxial compression test and an indoor permeation test were conducted. Based on the method of the region-weighted average, the corresponding permeability coefficient and the elastic modulus of each splitting-compaction region were obtained. The quantitative relationship between the mechanical properties and the impermeability of the soft filling medium before and after grouting was established. The results revealed that three different types of veins were formed as the distance from the grouting holes increased; namely, skeleton veins, cross-grid grouting veins, and parallel dispersed grouting veins. The thicknesses of the grouting veins decreased gradually, whereas the number of grouting veins increased. Moreover, the strikes of the grouting vein exhibited increased randomness. The reinforcement effect of segmental split grouting on soft filling media was mainly confirmed by the skeleton support and compaction. The elastic modulus of the grouting reinforcement solid increased on average by a factor that was greater than 100, and the permeability coefficient decreased on average by a factor that was greater than 40 in the direction of the parallel grouting vein with the most impermeable solid. The research results may be helpful in the investigation of the split grouting reinforcement mechanism under the condition of segmented grouting.

Experimental Study on Compressive Property of Concrete Corroded by Seawater in Low-Temperate

2010 ◽  
Vol 29-32 ◽  
pp. 1872-1877
Author(s):  
Ying Zi Zhang ◽  
Ying Fang Fan ◽  
Hong Nan Li ◽  
Xue Nan Wu
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Major Ions ◽  
Damage Index ◽  
Physical And Mechanical Properties ◽  
Concrete Specimen ◽  
Compressive Property ◽  
Accelerated Corrosion ◽  
Surface Mass ◽  
Degradation Ratio

In order to investigate the compressive property of the concrete corroded by seawater in low-temperature, compressive tests are conducted on concrete specimen, which are corroded by accelerated corrosion method. Artificial seawater solution (Major ions concentration are five times of yellow seawater), are applied as the corrosive medium in the laboratory. Uniaxial compressive mechanical properties of the concrete tests, including 60 prism concrete specimens, are carried out. The physical and mechanical properties (including surface, mass, compressive strength, elastic modulus et al) of concrete in the different corrosion degree are researched. Taking the strength degradation ratio and elastic modulus loss as damage index, effects of the corrosion solution on the property of corroded concrete are discussed in detail. Relationships between the damage index and corrosion state of specimens are achieved.

scholarly journals Research on Influence of Water-Cement Ratio on Reinforcement Effect for Permeation Grouting in Sand Layer

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Zhipeng Li ◽  
Lianzhen Zhang ◽  
Yuntian Chu ◽  
Qingsong Zhang
Keyword(s):  
Deformation Modulus ◽  
High Water ◽  
Sand Layer ◽  
Curing Time ◽  
Reinforcement Effect ◽  
Cement Slurry ◽  
Permeation Grouting ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Grouting Reinforcement

In order to study permeation grouting reinforcement effect in the sand layer, a set of grouting test device is developed, which consists of a power device, a pressure-bearing slurry tank, and several test frames. Compressive strength, deformation modulus, and permeability coefficient are selected to be the evaluation index of grouting reinforcement effect. Grouting reinforcement effect under different water-cement ratio of cement slurry and curing time were measured. Eventually, under laboratory conditions, fitting formulas have been obtained which describe the quantitative relationship between reinforcement effect of permeation grouting and water-cement ratio and curing time. Results show that water-cement ratio of slurry has obvious effect on grouting reinforcement effect. Mechanical performance and impermeability of the grouted body are negative-correlated with water-cement ratio. There are two different destruction patterns for the grouted body in uniaxial compression process: global destruction pattern at low water-cement ratio and local destruction pattern at high water-cement ratio. If cement slurry at high water-cement ratio is permeated into the sand layer, water bleeding phenomena will appear and lead to inhomogeneous performance of the grouted body, with lower performance in the upper part and higher performance in the lower part of the grouted body.

Integral Risk Analysis as a Supporting Framework for Water Quality Management

1991 ◽  
Vol 24 (10) ◽  
pp. 343-346 ◽  
Author(s):  
H. R. Bos ◽  
C. T. Bowmer ◽  
M. C. T. Scholten
Keyword(s):  
Marine Environment ◽  
Marine Ecosystem ◽  
Water Quality Management ◽  
Quantitative Relationship ◽  
Complex Signals ◽  
End Effects ◽  
The North ◽  
Lack Of Information ◽  
The North Sea

The prevention of pollution in a marine ecosystem such as the North Sea has traditionally been approached from two angles i.e. (1) by controlling the disturbance at source and (2) by monitoring the quality of the marine environment and act when deleterious effects occur. These approaches are loosely based on the precautionary principle and on the concept of assimilative capacity, respectively. Although in principle different approaches, they are similar in practice as they both accept, rightly or wrongly, a certain input of pollutants to the marine environment. There remains however, a stubborn lack of information as to what qualitative and quantitative relationship exists between the input(s)/sources and consequently the distrubance or effects in the marine environment. Environmental stress in a marine ecosystem becomes visible when the dynamics of its elements deviate from their normal cycles or fluctuations. These observable end-effects are often the initial reason for concern, i.e. long after the process of disturbance is underway. It has always been difficult to interpret these mostly complex signals and relate the observations to primary causes. In order to handle the diversity of information and signals in the cause-effect chain between input(s)/sources and disturbance, the development of a comprehensive logic framework is needed.

Study on Cracking of Anchor Structure due to Reinforcement Corrosion

2013 ◽  
Vol 652-654 ◽  
pp. 1315-1318
Author(s):  
Wan Tao Ding ◽  
Jin Hui Liu ◽  
Shu Cai Li
Keyword(s):  
Maximum Tensile Stress ◽  
In Situ Stress ◽  
Reinforcement Corrosion ◽  
Underground Engineering ◽  
Structure System ◽  
Deterioration Mechanism ◽  
Anchor Structure ◽  
Stress Ratios ◽  
Cracking Mode

Reinforcement corrosion is one of the main causes for the deterioration of reinforcement concrete structure. And it seriously affected mechanical properties of anchor structure system of underground engineering under complicated erosion environment. Based on elastic theory and assumption of maximum tensile-stress failure criterion, together with construction process of anchor structure and rust expansion critical process, reinforcement rust expansion mechanical model of anchor structure system was simplified. Elastic criterion of different initial cracking mode was rewarded under different stress ratios. According to analysis of critical cracking mode of different medium, cracking order of mortar and surrounding rock depended on their material parameters, in-situ stress and thickness of mortar cover. Critical cracking conditions of different medium without effect of in-situ stress was rewarded. The result provides a useful reference for analysis of mechanical deterioration mechanism of anchor structure and design of support structure of underground engineering.

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