问题
单项选择题 案例分析题
某深埋隧道为圆形隧道，半径为4．0m，围岩水平应力与垂直应力相等，应力为P=1000kPa，围岩中塑性区半径为10m，围岩内聚力c=20kPa，内摩擦角为30°，按芬纳（Fenner）公式计算。
若使支护抗力为0，松动圈半径应为（）。
A.4m
B.10m
C.13m
D.15.5m
答案
参考答案：D
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某深埋隧道为圆形隧道，半径为4．0m，围岩水平应力与垂直应力相等，应力为P=1000kPa，围岩中塑性区半径为10m，围岩内聚力c=20kPa，内摩擦角为30°，按芬纳（Fenner）公式计算。
若使支护抗力为0，松动圈半径应为（）。
A.4m
B.10m
C.13m
D.15.5m
参考答案：D
| The field of medicine has always attracted its share of quacks and charlatans — disrepu-table women and men with little or no medical knowledge who promise quick cures at cheap prices. The reasons why quackery thrives even in modem times are easy to find. To begin with, pain seems to be a chronic human condition. A person whose body or mind "hurts" will often pay any amount of money for the promise of relief. Second, even the best medical treatment cannot cure all the ills that beset men and women. People who mistrust or dislike the truths that their physicians tell them often turn to more sympathetic ears. Many people lack the training necessary to evaluate medical claims. Given the choice between (a) a reputable physician who says a cure for cancer will be long, expensive and may not work at all, and (b) a salesperson who says that several bottles of a secret formula "snake oil" will cure not only cancer but tuberculosis as well, some individuals will opt for "snake oil". Many "snake oil" remedies are highly laced with alcohol or narcotic drugs. Anyone who drinks them may get so drunk or stoned that they drown their pains in the rising tide of pleasant intoxication. Little wonder that "snake oil" is a popular cure-all for minor aches and hurts! But let there be no misunderstandings. A very few "home remedies" actually work. However, most remedies sold by quacks are not only useless, but often can be harmful as well. |
To evaluate medical claims, one must______.
A．turn to reputable doctors
B．make an adequate choice
C．have the necessary training
D．disbelieve promise of relief
