风化砂掺量及上覆荷载对改良膨胀土的影响试验

Research on Influence of Overburden and Weathered Sand on Modified Expansive Soil

鉴于公路膨胀土路基的合理覆土深度的确定是膨胀土路基设计的一个关键问题,以小溪塔至鸦鹊岭一级公路改建工程膨胀土路基处理为背景,对采用风化砂改良后的膨胀土做了膨胀力试验及在不同上覆荷载作用下的有荷膨胀率试验,即对原膨胀土及膨胀土中掺入10%、20%、30%、40%、50%的风化砂,分别在杠杆式标准固结仪上做膨胀力试验,并在杠杆式标准固结仪上按0、12.5、25.0、37.5、50.0、75.0kPa做六级加载试验。试验结果表明,随着风化砂掺量的增加,膨胀力显著下降,同一掺砂比例下掺砂土的膨胀率与上覆荷载常对数呈线性关系,同一上覆荷载作用下掺砂土的膨胀率随掺砂比例的增加先增大后减小,可推断不同深度处膨胀土可能发生的变形量,进而确定工程上处理膨胀土时需覆土的深度。

How to determine the rational soil cover depth of highway expansive soil roadbed is a key problem of ex- pansive soil roadbed design. Expansive force experiment and loaded swelling ratio experiment under different overburden of weathered sand modified expansive soil have been implemented in this paper. Undisturbed soil and expansive soil mixed with 10% ,20% ,30%,40%, 50M of weathered sand have been carried out expansive force experiment on the lever type standard consolidation apparatus. Undisturbed soil and expansive soil mixed with 10%, 20%, 30%, 40%, 50% of weath- ered sand have been done loaded swelling ratio experiment according to 0 kPa,12.5 kPa,25.0 kPa,37.5 kPa,50.0 kPa, 75.0 kPa six stage loading on lever type standard consolidation apparatus. Experimental results show that with the in- creasing of dosage of weathered sand, expansive force decreases significantly; the expansive ratio of the same sand ratio be- tween the overlying load logarithm is linear relationship; under the same overburden loads, the expansive ratio of swelling soil mixed with weathered sand firstly increases and then decreases. Through the experimental research, the possible deformation of different depths can be inferred. Furthermore, the needed thickness of expansive soil can be rationally designed in engineering.