FIELD EXPERIMENTAL STUDY ON TRAITS OF GROUTING IMPERVIOUS CURTAIN IN SOFT LAYER

The high permeability of loose formation, the large consumption plasma of anti-seepage grouting and irregular diffusion have a great deal of uncertainty. So, it is very difficult to accurately grasp the structural traits of the formed impervious curtain, which contains impervious curtain thickness, mechanical properties, anti-seepage effect and other elements. Existing methods and techniques on the assessment of impervious quality mainly include that water pressure test, standard grout depth, coring, physical probe and other methods to access relevant information, which would impose a direct effect. In this study, injection test, hole skew measurement, coring test, whole section excavation and other methods are applied in field, the characters of anti-seepage structure include curtain effective thickness and its sphere of influence, curtain strength properties and permeability characteristic. They are revealed by experimental tests in various operating conditions. Under the condition of 1.5m pitch-row and 0.8m double-row distance, the experimental results show that it is very simple and efficient to adopt the technique of slurry sealing means and pulsating grouting ways to control the grouting process and the utilization of controllable clay grout material with appropriate grouting control parameters. Meanwhile, the periphery hole compaction zone, effective body and cemented stones curtain body are formed uniform and effective. The seepage coefficient reaches 5 lu below. The 28days stone strength after grouting reaches over 3.0MPa. In the effect contrast to pulp and stable slurry paste perfusion, it is found that if grout with stable slurry, it will be mainly with splitting permeability and the diffusion distance will be further than pulp. For higher seepage reinforcement requirements engineering, it will be the best to do the paste perfusion first, and then the stable slurry irrigation. Pulp veins mainly concentrate in the 1m radius around the grouting pipe, accounting for more than 60% of the total grouting volume. It can form an effective impervious body. The soil within 1.0m generates a significant displacement and outside 1.5m generates a small displacement. Grouting technology and parameters can be directly applied to the similar formations of layer. It is necessary to develop a physical model for studying in a large sample for the grouting construction characters of different types of formations in different grouting materials, grouting process and grouting parameters. The main conclusions include the following three parts. The first one is to propose grouting structure traits conceptual model for the characteristics of the soft ground.The process of closing slurry, pulsating grouting, and controllability clay grout material are suitable and clear for construction control perfusion parameters. Excavation pulp veins show a clear outcome. Compaction of cement and overlapping curtain grouting shows effectively the process of grouting and controlling parameters. All can be directly applied to similar projects. The second one is to improve the proposed measures to improve the structure of traits: analyze grouting formation effectively, select grouting process in line with the characteristics of the formation, research and experimental hole data sufficiently to determine the formation groutability, choose the appropriate grouting material, hole distance, grout volume and grouting pressure. The third way is to take the excavation which can be directly observed plasma pulse shaping and stone body. But the cost is pretty high. To understand the grouting structure traits of the different types of formations in different grouting materials, grouting process, and different grouting parameters, developing physical model and obtaining valuable results through large sample laboratory tests are needed next.