The Research Of The Experiment Of Mud Pump Dams-the Test Of Pipe Drainage Optimization For Building Check Dam Using Mud Pump In Middle Silt Loam Area

This paper researches the best way of drainage pipeslines to build check dam by usingmedium silty loam in Zhidan, Shaanxi province. This study includes three parts: firstly,analyze the physical mechanical features of the soil and the feasibility of this method basedon the regulation of water conservancy and hydropower and test methods of soils; secondly,do the actual setting drainage pipes experiment by laying pipes into the check dam to test theprogress of drainage and measure the displacement of drainage pipes, this experiment lead toclear the effect of different ways of setting drainage pipes, and to guide subsequent plotsimulation experiment; thirdly, build the simulation plot to choose the best way to build thecheck dam by comparing three cases of mud(soil-water ratios were1.0、1.5and2.0) in threetypes of pipes laying method, three kinds of grouting height of the drainage experiment. Theresults are as follows:(1) the soil test results showed that the selected soil in Zhidan is fine-grained soil. Thecharacteristic values of physical mechanics included that plasticity index (IP)>0.73x (wL-20)and IP>10, liquid limit wL<50%. It indicated that this soil belongs to the low liquid limitclay and silty loam and the properties of soil are between the high compressibility of soil andthe compressibility of soil.The mechanical composition of this soil was bad, but the water permeability was strong.the soil can be used as the sluicing-siltation earth dam because the soil satisfy the technicalspecification for sluicing-siltation earth dam (SL302-2004). Therefore, the soil was applicableto the mud dam test. (2) the pipes drainage experiment results showed that the total drainage rate of pipesaccounted for the total water in the test in the10days is14.64%. the result indicated that theeffect of pipes drainage was good.Drainage process line showed that when the mud not completely submerged the pipes,the effect of drainage was good; but after the mud completely submerged the pipes, therewere almost no drainage; Drainage effect changed better obviously when the mud submergingthe vertical pipes, adding the horizontal drainage pipes to speed up the mud drainage effectwas not obvious. Accordingly, the area simulation test determined to compare drainage effectof three pipes laying methods(horizontal pipes layout、vertical pipes layout and combinationpipes layout).(3) the results of plot simulation drainage tests showed that:The order of ultimate displacement of mud with the same soil-water ratio but different pipeslayouts under different filling rate was combination pipes layout> vertical pipes layout>horizontal pipes layout. Displacement of the first two were close but different from thehorizontal pipes layout. The higher the filling height, the greater was the difference, but thedisplacement of combination pipes layout and vertical pipes layout became more closer. Inconclusion, this paper suggested that we should choose the only setting vertical pipes layoutto build the check dam and abandon the combination pipes style due to the economic factor.The ratio of the displacement in the first12h and the total moisture content of mud withthe same soil-water ratio but different pipes layouts(vertical pipes layout and combinationpipes layout) under different filling rate was over70%, this rate can even reach above90%when the soil-water ratio was small; While the rate of the displacement in the first12h andthe total moisture content of mud was below50%when pipes layout was horizontal pipeslayout. Therefore shortening the incubation time appropriately after grouting andappropriately increasing the grouting height can shorten the construction time of a dam withvertical pipes or combination pipes as the drainage system.When the soil-water ratio were1.0and1.5, The ratio of the displacement and the totalmoisture content of mud of vertical pipes layout or combination pipes layout was far greaterthan that of horizontal pipes. This indicated drainage effects of vertical pipes layout orcombination pipes layout was more better than that of horizontal pipes. but when soil-water ratio was2.0, the drainage effects of three kinds of pipes layouts were close, the drainageeffects vertical pipes did not reflect the significant advantages.With the increase of grouting height, the actual water content of the mud would beincreased, while the first12h ratio was substantially remain the same, which showed thatelevating the grouting height can give full play to the effects of pipes drainage.Grouting height impact on the effects of pipes drainage with the same soil-water ratio andsame pipes layouts was not obvious, so appropriately increasing the grouting height of oneday can make full use of the slurry preparation equipment, speed up the construction progressand shorten the construction time of a dam.Along with the increase of the soil-water ratio, the actual water content decreased. Waterdischarged more easily in72h, which made the displacement of three pipes layouts closer.Considering the drainage speed of vertical pipes and combination pipes was faster than that ofhorizontal pipes, vertical pipes and combination pipes should be selected preferentially.With the increase of soil-water ratio, the ratio of the displacement in the first12h andthe total moisture content of mud under three pipes layouts was all declined, which indicatedthe effect of pipes drainage was declined. However increasing the soil-water ratio was one ofthe research directions of building check dam by mud pump, which can also effectivelyshorten the construction time, so the drainage pipes network system should be furthervalidation and improvement.