单桩在轴向受压荷载作用下的常见的破坏模式有哪几种？各在什么情_爱下问搜题

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问题问答题简答题

单桩在轴向受压荷载作用下的常见的破坏模式有哪几种？各在什么情况下出现？其承载力由什么决定？

答案

参考答案：

在轴向受压荷载作用下单桩的破坏是由地基土强度破坏或桩身材料强度破坏所引起。在工程实践中几种常见的破坏模式如下：⑴当桩底支承在很坚硬的地层，桩侧为软土层，其抗剪强度很低时，桩在轴向受压荷载作用下，如同一受压杆件呈现纵向挠曲破坏，桩的承载力取决于桩身的材料强度。⑵当具有足够强度的桩穿过抗剪强度较低的土层而达到强度较高的土层时，桩在轴向受压荷载作用下，由于桩底持力层以上的软弱土不能阻止滑动土楔的形成，桩底土体将形成滑动面而出现整体剪切破坏，桩的承载力主要取决于桩底土的支承力，桩侧摩阻力也起一部分作用。⑶当具有足够强度的桩入土深度较大或桩周土抗剪强度较均匀时，桩在轴向受压荷载作用下，将出现刺入破坏，基桩承载力往往由桩顶容许沉降量控制。

单项选择题

阿米巴病组织损伤主要是由什么引起的

A．溶组织内阿米巴的机械性损伤

B．溶组织内阿米巴释放的毒素

C．迟发型变态反应

D．继发感染

E．溶组织内阿米巴的接触性溶解细胞作用及水解酶使组织破坏

完形填空

完型填空（共20小题；每小题1.5分，满分30分）
阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中选出可以填入空白处的最佳选项。
For long, a little boy was wondering why his deskmate could rank 1^st in the class whenever he wanted to, while he himself failed to: he only ranked 21^st.
At home, he asked his Mom, “Mom, am I more 21 than others? I feel I am obedient and as careful as him, but 22 I always fall behind? ” Hearing the words， Mom was aware that her son began to 23 the sense of self-respect, which was now being injured by the ranking system. 24 at him, she went wordless, not knowing 25 to explain.
In another test, the son ranked 17^th, while his deskmate remained 1^st. Back home he 26 the same question. Mom really wanted to inform his son that 27 differs, which means that students ranking 1^st are supposed to be cleverer than normal ones. 28 , was this discouraging answer the one that her son was constantly 29 about? Thank goodness she did not open her mouth.
H

ow to answer her son’s question? There were times when she felt an urge to say, “You are too lazy. You are not as hard-working as others…”but she stopped   30  imagining her son suffering from the pains of unsatisfied grades and rankings. She thought it   31  to put any additional burden on his son and was trying to find out a perfect answer.
Time passing swiftly, the son   32 primary school. Despite studying harder and better, he was still unable to keep up with his deskmate. To show her pride of him, Mom decided to   33 him to the sea. During the trip, she managed to give an answer.
Now, the son no longer worries about his   34 , and there are no boring guys who would inquire his grades in primary school, because,   35  the 1^st ranking, he is admitted to Tsinghua University. Back home in winter vacation, he was invited to   36 the students and parents in his high school, In the speech, he mentioned a valuable experience in his childhood, “…When my mother and I were lying on the   37 , she pointed to the front and said, “Do you see the seabirds struggling for food over there ?When the waves come near, little birds can rise   38 while awkward seagulls would take more time to complete the process. However, have you noticed birds that finally fly 39 the endless ocean are none other than the awkward seagulls?” The speech   40  many mothers present to tears, including his mother.

A．considerate

A．intelligence

A．enthusiastic

C．disappointed