比薩斜塔為何能經(jīng)歷4次大地震而不倒？

雖然有5度的傾斜度，但58米高的比薩斜塔自1280年以來(lái)經(jīng)歷至少4次大地震，為何還能屹立不倒?科學(xué)家最近給出了答案。

New research has revealed how the iconic Leaning Tower of Pisa has managed to stay standing – and intact – in the face of four strong earthquakes and a precarious lean of five degrees.

意大利的標(biāo)志性建筑比薩斜塔有5度的傾斜度，而且還歷經(jīng)4次大地震，卻依然屹立不倒，完好無(wú)損，最新的研究揭開(kāi)了這個(gè)謎底。

The vulnerability of the Unesco World Heritage Site has mystified engineers and scientists for millennia. Moderate seismic activity was expected to significantly damage the 58m tall Tower, or even result in collapse but, incredibly, this has not happened.

比薩斜塔高58米，被評(píng)為聯(lián)合國(guó)教科文組織世界遺產(chǎn)。一千年來(lái)，比薩斜塔的脆弱性一直令工程師和科學(xué)家們困惑不已。按說(shuō)，中度地震活動(dòng)應(yīng)該就能導(dǎo)致它嚴(yán)重受損甚至倒塌，但現(xiàn)實(shí)中這樣的情形并未發(fā)生，令人不可思議。

A research group of 16 engineers at the University of Bristol has now discovered that the considerable height and stiffness of the Tower, combined with the softness of the foundation soil, ensure it doesn’t resonate with earthquake ground motion.

英國(guó)布里斯托爾大學(xué)一個(gè)由16名工程師組成的研究小組如今發(fā)現(xiàn)，比薩斜塔如此的高度及其堅(jiān)硬的建筑材料與松軟的地基土壤結(jié)合在一起，使它不會(huì)與地震發(fā)生時(shí)的地表活動(dòng)產(chǎn)生共振。

This phenomenon is known as dynamic soil-structure interaction (DSSI) and the Tower now holds the auspicious title of world record holder in DSSI effects.

這種現(xiàn)象被稱(chēng)為“土壤-建筑結(jié)構(gòu)”動(dòng)態(tài)相互作用(DSSI)，幸運(yùn)的是，比薩斜塔現(xiàn)在是DSSI效應(yīng)的世界紀(jì)錄保持者。

“Ironically, the very same soil that caused the leaning instability and brought the Tower to the verge of collapse, can be credited for helping it survive these seismic events,” said Professor Mylonakis, head of the Earthquake and Geotechnical Engineering Research Group at the University of Bristol.

布里斯托爾大學(xué)地震與巖土工程研究小組負(fù)責(zé)人米洛納基教授說(shuō)：“有意思的是，導(dǎo)致斜塔傾斜不穩(wěn)、幾乎要倒的土壤也是幫助它挺過(guò)這些地震活動(dòng)的功臣。”

The Tower continues to attract visitors keen to marvel at this remarkable architectural feat. Construction on the Tower began in 1173 and continued for about 200 years due to the onset of a series of wars.

比薩斜塔一直吸引著大量游客前來(lái)，人們驚嘆其卓越的建筑成就。比薩斜塔始建于1173年，由于多次戰(zhàn)爭(zhēng)來(lái)襲，建筑時(shí)間持續(xù)了大約200年。

Multiple efforts to maintain the historic structure have occurred over the years. In the 1920s, the foundations were injected with cement grouting with the intention of stabilising the Tower, while in 1990, a decision was made to completely close the site to visitors due to fears it was at risk of toppling.

多年以來(lái)，人們?yōu)榫S護(hù)這一歷史建筑做出多次努力。在上世紀(jì)20年代，人們?cè)谄涞鼗凶⑷肓怂喙酀{，以穩(wěn)定塔身。在1990年，由于擔(dān)心會(huì)倒塌，相關(guān)部門(mén)還決定將比薩斜塔完全對(duì)游客關(guān)閉。

It was the first time the Tower had been closed in 800 years. It reopened again in 2001 and remains one of Italy’s most popular tourist attractions.

這是比薩斜塔近800年來(lái)首次對(duì)游客關(guān)閉。比薩斜塔在2001年重新開(kāi)放，仍是意大利最著名的旅游景點(diǎn)之一。