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我在四川省川滇公路工作时,看到当地有很多石梁小桥,跨度约3～7公尺,桥身是一排石梁,两端桥台也是石垒的。这些桥修建的年代,大约已有一二百年。如叙永的“礼送江桥”是明历中修建的,纳溪有一座桥据说是吴三桂进兵时为运兵而建的,但奇怪的是,每根石梁下面都有一根木梁。以往,我知道内地有些梁式古桥如西安的普济,灞、滻、丰四桥,福建泉州桥都是木梁。因为石头的抗拉强度不大,只宜于发券(音旋)做石拱,如果做梁或梁式桥走人行车,恐怕不到几年,就会自底面开裂而断坏。尤其是从前的骡马大车,车轮不圆,载重又大(一吨),车行时震击桥面的力量是很大的。而这些3～7公尺长的石梁桥能够挺住这么久,和那根木梁多少是有点关系的。怀着这个疑问,我见人就问,终于从一位朋友那里打听出来,使我对劳动人民的智慧肃然起敬。原来这是
When I was working at Sichuan-Yunnan Highway in Sichuan Province, I saw a lot of Shiliangqiao bridges spanning about 3 to 7 meters. The bridge was a row of stone beams, and the abutments on both sides were also stone barriers. These bridges were built about a hundred years ago. If Xu Yong’s “gift to send Jiangqiao” was built in the Ming calendar, a bridge in Naxi is said to be built for the troop movement when Wu Sangui troops into the army, but strangely, there is a wooden beam below each stone beam. In the past, I knew that some beam-type ancient bridges in the Mainland, such as Puji, Mi, Mi, Feng Siqiao in Xi’an and Quanzhou Bridge in Fujian Province are wooden beams. Because of the small tensile strength of stones, it is only advisable to issue stone vaults (phonetic spiral) to do stone archs. If a beam or a beam bridge is left for driving, I am afraid that in less than a few years cracking will occur from the bottom. In particular, the old mule cart, the wheel is not round, heavy and heavy (one ton), when driving shocks the strength of the bridge deck is great. And these 3 to 7 meters long stone beam bridge can hold it for so long, and how much wood beam is a little relationship. With this question, when I saw the people, I finally inquired from a friend and aroused my respect for the wisdom of the working people. This is the original