实验通过对膨润土基回填材料的配比、干密度、孔隙率、含水率和环境温度等因素研究发现,膨润土基回填材料的导热性能主要是由骨料(石英砂)含量、干密度和孔隙程度共同决定的,环境温度对回填材料导热性影响较小。含水率应合理控制,适宜配比、正确回灌能有效提高导热性和地下热交换器的工作效率,工程收益率高。

Make an experiment on the influence of composition,density,porosity, water content and temperature on the borehole backfill materials.The research results indicate that the thermal conductivity of bentonite backfill material is determined by the quartz sand content,density and porosity.The thermal conductivity with temperature is slightly higher,and water content should be reasonablely controlled.Suitable composition, correct backfill can effectively improve the thermal conductivity and the underground heat exchanger efficiency,and acquire an high project benefit.

为改善土膨润土竖向隔离墙材料的分散性，增强隔离墙阻滞污染物能力，对添加3种不同磷酸盐分散剂的土膨润土回填料进行了黏度试验，研究了不同分散剂掺量下回填料表观黏度的变化规律．试验结果表明：3种磷酸盐分散剂均可显著减小土膨润土回填料表观黏度；分散剂掺量从0％增加到0.1％，回填料表观黏度急剧下降，继续增加分散剂掺量，回填料表观黏度趋于平稳或略有增长；添加磷酸盐分散剂后，增加膨润土含量对回填料分散性影响不大，可通过添加磷酸盐分散剂的方法提高回填料对膨润土的负载量；六偏磷酸钠分散效果稍优于三聚磷酸钠和焦磷酸钠．同时，建议0％，5％，10％膨润土含量回填料对应的3种分散剂最优掺量为0.05％，0.1～0.5％，0.5％．磷酸盐分散剂在改善隔离墙材料分散性、提高墙体对污染物的阻滞能力方面具有潜在的工程实用价值．

Three types of phosphate dispersants,including sodium hexametaphosphate,sodium tri-polyphosphate and sodium pyrophosphate,are added to the soil-bentonite backfill in vertical cutoff wall in order to improve dispersed structure of the backfill and enhance its performance of mitiga-ting contaminants.The apparent viscosity of the backfill amended with dispersant is measured and the relationship between the dispersant content and the apparent viscosity of the backfill is studied. The test results show that the apparent viscosity reduces significantly when the backfill is amended with three types of dispersants.The apparent viscosity decreases sharply when the dispersant con-tent is increased from 0% to 0.1%,while further increase makes the apparent intensity maintain stable or show a slight rebound.Due to the negligible effect of bentonite content on the disperse property of the backfill amended with dispersant,the bentonite loading of the backfill can be in-creased by the addition of disp

在搅拌摩擦点焊过程中，通过添加填充板来改善摩擦成形过程，这种新工艺被称为回填搅拌摩擦点焊。分别采用回填搅拌摩擦点焊和传统的搅拌摩擦点焊工艺焊接 AA6061-T6搭接焊样品，研究搅拌头的旋转速度对接头的力学性能和金相组织的影响。在不同的旋转速度下，回填搅拌摩擦点焊接头的静态剪切强度都比传统搅拌摩擦点焊接头的好。这归因于在回填搅拌摩擦点焊时，添加了填充板从而有更多的材料来填充孔洞，消除了形成的孔洞缺陷，从而使点焊焊核区的有效截面积增加。借助扫描电镜观察讨论了材料的失效机制，分析了断裂表面形貌。2种焊接接头的硬度曲线都呈W形，最小的硬度出现在热影响区。

Friction stir spot welding with refilling by friction forming process (FSSW-FFP) was successfully modified using filler plate. Both of this new refilling technique and conventional friction stir spot welding (FSSW) process were used to weld Al 6061-T6 lap shear specimens and the results were compared. Effects of tool rotational speeds on mechanical and metallurgical properties in both the cases were studied. Static shear strength of refilled weld samples was found to be better than those welded by conventional FSSW process at all tool rotational speeds. This is explained in terms of effective increase in cross-sectional area of weld nugget due to addition of more material from filler plate, thereby eliminating the probe hole. Failure mechanisms were discussed and fracture surfaces were analyzed through scanning electron microscopy (SEM). The hardness profile of the welds exhibited a W-shaped appearance in both the processes and the minimum hardness was measured in the HAZ.

坑道施工中，超挖回填材料性能对衬砌的受力分布有较大影响。基于FLAC 3 D有限差分数值计算软件，模拟坑道开挖施工，通过改变回填层的弹性模量和厚度，分析了不同回填介质对衬砌结构弯矩和位移的影响，并比较了不同围岩级别对衬砌结构的弯矩影响。计算结果表明：1）拱顶、侧墙和底板的最大弯矩随弹性模量的增大而减小，弯矩开始降幅较大，但最终趋于平缓；拱顶、侧墙和底板的最大弯矩随回填层厚度的增大而增大，几乎成线性增加。2）拱顶和底板的最大位移随弹性模量的增大而增大，侧墙反之；拱顶和侧墙的最大位移随回填层厚度的增大而增大，底板则基本保持不变。

In tunnel construction,overbreak backfill material has great influence on the distribution of the internal force of the tunnel lining.In the paper,the tunnel excavation is simulated on basis of FLAC 3 D finite difference numerical software and the influence of different backfill materials on the bending moment and displacement of the lining structure is analyzed by changing the elastic modulus and the backfill layer thickness.The impact of different surrounding rock grades on the bending moment of the lining structure is also compared.The results show that the maximum bending mo-ment of the crown,sidewall and floor slab decreases as the elastic modulus increases,and it decreases dramatically at first and starts faster and smaller,and tends to decrease gently in the end;the maximum bending moment of the crown, sidewall and floor slab increases almost in linear as the thickness of the backfill layer increases;The maximum displace-ment of the crown and floor slab increases as the elastic

基于地源热泵单U地埋管二维换热模型，以钻孔内的换热热阻为目标函数，以回填材料导热系数、两埋管间距及管内水流速等参数为优化变量，利用添加了精英保留及迁移优化的遗传算法，对各参数同时变化时进行了目标函数优化，并分析了各参数对热阻性能影响，当回填材料导热系数、两埋管间距及流速均为最大值时，其对应的钻孔内换热热阻达到最小。研究结果对优化地埋侧换热器的设计具有一定参考价值。

Based on the two-dimensional heat transfer model for single U pipe in GSHP (Ground Source Heat Pump)system,this paper analyzed the influences of main different multi-variables on the heat resist-ance,including the heat conductivity coefficient of backfill materials,the buried pipe spacing in the bore-hole and the water velocity in the pipes.Improved Genetic Algorithm (IGA),in which elitism selection and migration were combined,was used to optimize the heat resistance in the borehole based on foregoing multi-variables.According to the optimized result,the minimum heat resistance was obtained when the heat conductivity coefficients of backfill materials,the buried pipe spacing and the water velocity in the pipes reached their maximal designed values.The results are useful for the optimization of the heat ex-changer design of GSHP.