基于响应面的基坑双排桩优化研究

OPTIMIZATION RESEARCH OF PIT DOUBLE-ROW PILES BASED RESPONSE SURFACE

基坑双排桩的方案设计需兼顾支护结构的安全性和经济性,因此双排桩的优化研究具有重要意义。以双排桩嵌固深度L、桩径d、桩间净距t、前后排桩净距B、连梁高度h的5个指标为设计参数,以最大水平位移、地表最大沉降、抗倾覆稳定性系数、整体稳定系数为4个约束条件,通过均匀试验方法和ACE非参数回归技术,基于杆系有限元建立双排桩设计参数与约束条件等变量的响应面;同时,以双排桩每延米的工程造价为优化目标函数,在响应面的基础上结合枚举法进行优化设计。通过算例分析,结果表明,基于响应面的双排桩优化算法具有高效和稳定的特点,并且能考虑多参数及其相关性对优化目标的影响;优化后的双排桩排距约为桩径的3.5倍,嵌固比约为1.3,土压力以前排桩所受土压力为主,抗倾覆稳定性为关键约束条件;此外,在没有显著增加变形和降低稳定性系数的条件下,优化方案较原设计方案每延米造价减少了23%。研究成果可为双排桩优化设计提供理论依据和技术支撑。

Optimization research of double-row piles （DRP）is a key considering both safety andeconomy in the design of DRP. The embedded depthL,pile diameterD,net pile spacet,net rowspaceB,beam height h are considered as five design parameters,and the maximum horizontal displacement,the ground settlement,coefficient of anti-overturning stability,global stability coefficientare considered as four constraint conditions. The response surfaces between design parameters and constraint conditions are established based FEM method when uniform test method and ACE non parametric regression technique are used. The optimization design of DRP is achieved with enumeration methodbased on the response surfaces when the objective function is set as construction cost per meter of DRP.Through analysis of a case,the results show that：High efficiency and stability are the characteristics ofresponse surface-based double-row pile optimization and multiple parameters and their correlation effects can be considered in this optimization algorithm. The row space is about 3.5 times the pile diameter,and the embedded solid ratio is about 1.3. The front pile is the main part in bearing the earth pressure,and the anti-overturning stability is the critical constraint condition after optimization. The construction cost per meter of optimization design is reduced by 23% compared to the original design without increasing deformation and reducing stability coefficients significantly.