Study On The Effect Of Strong Drainage Group Holes On The Water-rich Slope

Groundwater is one of the important factors leading to slope instability.Groundwater that rains and rains infiltrated into the slope and cannot be discharged in time is often a direct cause of instability of the slope and may cause serious disasters.Water-rich slopes are widely found in the hot and humid regions of southern China,with large rainfall and high groundwater levels.By discharging the water in the slope,not only can the stability of the slope be enhanced,but also the economic cost of relying on the support means can be reduced.Therefore,scientific evaluation of slope stability and effective treatment of slope instability,we must first fully study the characteristics of slope seepage field and time-space dynamics.In order to rationally and effectively utilize the strong drainage holes and increase the stability of the rainy season slope,it is necessary to study the group hole effect under the strong drainage of the water-rich slope.This paper uses a combination of indoor model test,theoretical analysis and numerical simulation.Through the indoor model test,the distribution and change of the head in the slope of the water-rich slope under the strong drainage of the drainage hole are monitored,and then the group hole effect under the condition of strong drainage is studied.The test results show that the group hole effect when the drainage hole is drained makes the water level in the middle area decrease more,and the influence range in the vertical direction is larger than the horizontal direction,in the actual engineering hole design,the distance of the drainage hole should be shortened horizontally,and the spacing of the drainage hole should be increased vertically.Based on the indoor model test,Visual MODFLOW software was used to simulate the seepage field characteristics of double holes and group holes under strong drainage conditions.The simulation results show that the water level around the drainage hole is obviously reduced when it is drained,and the surrounding groundwater is obviously flowing to the drainage hole,the drainage hole affects the vertical direction more than the horizontal direction.Comparing the simulation results of double-hole drainage and group hole drainage,it can be clearly seen that the water level in the middle area is reduced more when the group holes are drained,and the group hole effect is more obvious.Finally,combined with the actual project,a typical roadside slope is taken as the research object,and the water-rich slope under rainfall conditions is simulated by Geostudio’s SEEP/W module,and The regulation effect of drainage holes on the seepage field of water-rich slope and the optimal drainage hole layout are studied.Due to the dual effects of rainfall infiltration and higher groundwater level,the water level at the foot of the slope first rises,and the original unsaturated region above the water line gradually transforms into the saturated region.The upper drain pipe acts as a trap for rainwater,and the lower drain pipe can effectively reduce the water table.Since the foot of the slope is the gathering area of the rainwater and the overflow of the groundwater,the drainage pipe is arranged below the groundwater level and the drainage effect is best in the area close the foot of the slope.After the drainage holes are arranged,the distribution of rainwater in the slope body is more uniform,and the groundwater saturation line near the drainage hole becomes slower and the water level decreases.The change of the hole length has a great influence on the drainage pressure reduction effect of the slope.The longer the drainage hole is,the better the drainage effect is.The hole length of the drainage hole should be determined according to the range of the slope drainage;The inclination angle of the drainage hole has an influence on the regulation range of the groundwater level,and the slope rate and the water level deepening demand should be considered when laying;Within a certain range,the drainage effect of the drainage hole increases as the spacing of the drainage holes increases.