Jiang Q.,Hohai University |
Cheng H.,North China University of Technology |
Chen J.,Jiangyin Peoples Government Key Project Construction Office
Modern Tunnelling Technology | Year: 2013
The fact of large-diameter slurry shield construction related to problems of high ground losses (caused by low cutting face pressures and high grouting pressures) is not sufficiently considered in transverse settlement trough theory. Therefore, a modified formula for the GAP parameter is proposed. Using the construction of the Chengjiang west road river-crossing tunnel in Jiangyin City as an example, a modified GAP parameter was incorporated into the modified Peck formula and the analytical solution based on the Sagseta theory in order to study the influence of large-diameter slurry shield construction on soft soil. It was verified that due to the equivalent ground losses caused by factors such as construction quality, under-pressure of the cutting face, and high grouting pressures, calculated settlements are larger, but are more consistent with the measured data and more reasonable theoretically.
Jiang Q.,Hohai University |
Chen J.,Jiangyin Peoples Government Key Project Construction Office |
Zhu J.,North China University of Technology |
ICPTT 2012: Better Pipeline Infrastructure for a Better Life - Proceedings of the International Conference on Pipelines and Trenchless Technology 2012 | Year: 2013
There is an annular space with mud surrounding the installed pipeline after the completion of the project using Horizontal Directional Drilling (HDD). The mud in the annular space is super saturated soil with rich water, moisture away with time decreases the mud pressure, the unloading changes the soil stress around the hole wall, causing stress redistribution and the shrinkage of hole wall, and what's even worse, a certain space will form around the pipeline and hole collapse and surface subsidence. The shrinkage after construction is the key factor for the project quality in the directional drilling engineering, the formula of the shrinkage of hole wall after construction is the main problem to be solved. Analyzing the rules of the secondary stress and the radius of plastic zone in soil layer through analyzing the soil stress surrounding the hole wall with the SMP failure criterion and elastic-brittle-plastic model about sandy soil, summing the rules of the secondary stress field and displacement distribution and deducing the calculation formula of the optimal mud pressure, radius of plastic zone and displacement. In addition, getting the value of the displacement through numerical simulation with the FLAC2D. It can be found that the displacement law curve and the hole wall displacement is proportional to the final hole radius and the cover depth of soil through contrasting the results of numerical calculation and numerical simulation. At the same time, through changing the value of internal friction angle and mud pressure with other conditions remain unchanged, getting that the more internal friction angle and mud pressure, the smaller displacement of hole wall, the greater the stability of the surrounding soils. Providing the reliable theory basis for analyzing the hole wall shrinkage of directional drilling in sandy soil areas. © 2013 American Society of Civil Engineers.
Zhu J.-M.,North China University of Technology |
Zhu J.-M.,Beihang University |
Zhao S.-S.,Beihang University |
Jiang Q.,Jiangyin Peoples Government Key Project Construction Office |
And 2 more authors.
Meitan Xuebao/Journal of the China Coal Society | Year: 2012
The post-construction ground settlement is the key factor for the project quality in the directional drilling engineering, the formula of the post-construction ground settlement is the main problem to be solved. The rules of the secondary stress-strain and the radius of plastic zone in soil layer with the SMP failure criterion and elastic-brittle-plastic soften model were analyzed, the calculation formula of the optimal mud pressure and the minimum mud pressure limited were deduced. The result computed based on the SMP is better than the result computed based on the M-C failure criterion, it can be well used to explain the mechanism of ground settlement in soft soil regions and guide engineering practice. Through changing the value of cohesion, internal friction and the dilatancy parameter, it can be found that the smaller of the cohesion and internal friction after soil yield, the greater of the radius of plastic zone, meanwhile, soil dilatancy has the function of preventing shrinkage.