Reduce and shake and study and let the urban life

Reduce and shake and study and let the urban life be quieter
Staff reporter Zhang ShuangHu

Because of the urban orbit traffic system ' Including the subway and overhead light railway of city) Have advantage such as being great, fast, safe and reliable of transporting amount, have already become and solved the effective means congested in traffic in the city. Having and building the city of the traffic system of the orbit and getting more and more at home, with the extension of the urban orbit, it is more and more outstanding that its environment brought shakes questions such as pollution,etc.. Supported by national natural science fund, " the environment that the urban rail transportation causes shakes and prevents and cures countermeasur e research " which Xia He, Professor of Communication University of Beijing, presided over Have carried on further investigation on this, and proposed reducing the vibrant serial measures of the building.

It is that one kind is polluted seriously that the environment is shaken

Have research institution until environment vibrant to survey the result, indicate live to the intersection of our country and several typical urban railway, the intersection of vibration and the intersection of acceleration and magnitudes of majority of area close to 80 within the 30 of centre line from orbit . " It shows to shake the test, when shaking the acceleration and reaching 65 decibels, there is slight influence on sleeping; While shaking the acceleration and reaching 69 decibels, all light persons who sleep will be woken; While shaking the acceleration and reaching 74 decibels, except that wakeless person, generally speaking, other people will wake. " Xia He says, " because the urban orbit traffic system is enormous in investment, once it is very difficult to build up and relocate and move, once the vibration pollution of the rail transportation takes shape and exists for a long time. So, set about studying and shaking the pollution law, shaking the reason, vibration to produce to propagate route and control method and having very important meanings. "

The traffic is shaken ' It is mainly that rail transportation is shaken) Mean structure caused by traffic vehicle shake and adopt the stratum around ' Underground or ground) Spread outwards, further bring out the underground structure and neighbouring building (including indoor furniture etc.) of adjacent place Two second-class for vibration sum noise. Traffic vibration will safe to structure building nearby especially building antiquated and some prec ision type instrument, resident, life, work of staff member exert an influence.

" Shake interference on residents and the building and influence in order to lighten the environment, domestic and foreign scholars have studied in a large amount, the building shakes the characteristic etc. to find the solution by oneself to attempt to shake the source intensity, cut off and shake and propagate the route, decay to shake the range, adjust near the traffic route through reducing, also made the good result. " Xia He says.

Studies have suggested, the traffic system of the orbit is vibrant to shake the source to mainly come from the following resp ects: The train loads impacts produced to the gravity of the orbit while running; The train is during operation, the vibration of wheel and rail structure produced in a rail interaction; When the wheel has rolled the rail is connected, the vibration of wheel and rail structure produced in a rail interaction; Damage of the smooth-going and wheel of the orbit,etc.. To overhead system of light railway, its influence factor mainly has train speed, vehicle weight, bridge structural type and basic type, span, rigidity, deflection,etc.. Meanwhile, the train and interaction of the bridge will be strengthened and shaken function sometimes. As to the underground, its influence factor mainly has train speed, vehicle weight, foundation of the tunnel and lines with and builds structural type, orbit type, adopts and separates and shakes the measure etc..

Look for the solution from a plurality of links

The train shakes the vibration of the ground building along the line caused, it shakes the size of grade with the structure form of the building, basic type and has close contacts with distance of the subway. Standing grain explain as to the intersection of foundation and good, than large top the intersection of armored concrete and building quality summer, because low natural frequency its, difficult to encourage, get up greater vibration, therefore it shake grade until whom soil transmit shake grade and having significant decay since, person who decay can reach 10- 20, from the intersection of subway and the intersection of tunnel and horizontal the intersection of dis tance and 32, survey and shake grade and is not greater than 60 decibels in the high-story building basement, more than one layer can not measure the vibration that the subway caused while going; The brick with general foundation can decay to mix the structural residential building by 5- 10 decib els; And the building with worse foundation, such as the light quality structure or building of the shallow foundation, there is few decaying amount, it shake grade until soil shake grade to be close, even will appear, shake greater than outdoor the intersection of ground and vibrant phenomenon in the room.

" The vibration that the traffic system of the orbit causes is transmitted to close to the structural t hinging through soil to cause and shake or destroy, so, must understand that make the wave and spread the characteristic in the earth's surface at first. Meanwhile, various of soil property met in project reality, very complicated, while studying the spread problem of the wave, also introduce the concrete parameter received in on-the-spot test and solve the vibrant fluctuation and dampen the problem. " Xia He says.

Vibrant to separate, hinder can wall and,etc. protective screen come, block, scatter and various diffraction come on, realize in conformity with Reeb by rivers and canals, rubbery the intersection of cushion and layer, sheet pile effectively. In elastic foundation, the open drain and filling three kinds of segregation modes of irrigation canals and ditches, elastic foundation, to to separate, shake effectual high frequency, because of elastic existence of foundation, speed and acceleration of maximum low frequency on the orbit will be enlarged, so no matter for operating the stationarity of the train or for the separating and shake of surroundi ng environment, the elastic foundation is not a very ideal method; As to open drain and filling irrigation canals and ditches, it is the deeper to reduce and shake the ditch, it is the better to reduce and shake the result, and it is wide to reduce and shake the result with the ditch and have nothing to do. To separating the vibration that the train caused, the open drain is the best in three ways, can totally cut off the spread of the shock wave. But on practical application, open drain have issue of stability, must set up, support the framework to enable their remain stable. Shake as to low frequency, the above-mentioned three kinds are not all big through shaking results that the measure causes.

From reducing and shaking the result and saying, the rubble railway roadbed is superior to the whole railway roadbed, but rubble railway roadbed have stability to be bad maintaining work load to be large conducting ones elf with dignity large, the intersection of orbit and the intersection of building and the intersection of height and relativ ely loud and easy shortcoming of polluting etc. of railway roadbed. So for subway, generally adopt the whole railway roadbed, among them it make sets of type short for pillow railway roadbeds, plastics pillow railway roadbeds wholes short whole, be be be be floated to can if you can't get up, if you can't get, if you can't reduce, if you can't bestir oneself, use to last several kinds of railway roadbed pattern theyses such as railway roadbeds wholes panel, etc.. No matter have, cut railway roadbed or whole railway roadbed, can cut or congeal soil, set up rubber, reduce, shake cushion under the board in line, adopt the appropriate spring secures rail to sleeper, can increase the elasticity of the whole railway roadbed. For example, in DTI type and Model DTV fastener that the subway uses of Beijing, the Model DTV fastener can be reduced and shaken 5- 8 decibels than the Model DTI fastener through te sting in the room.

Layer increases the elastic important component of the fastener in the elastic cushion, should improve the shortcoming of the whole railway roadbed, can adopt high elastic the intersection of cushion and layer, paste by high the intersection of damping and material and restrain compound the intersection of damp ing and board that panel commit from can reduce the vibration of the rail in the intersection of rail and surface. In order to canvass the reducing and shaking the result of board rail of damping, researchers are in Beijing Subway Line No. 13 Xizhimen - -Have installed the damping board on the rail of section of Dazhongsi, and right? Fierce tenon haze Qian buttocks short of money tenon haze Mi mother stop Liu's stewing stop not warmi Ng up to last deep blue Qian of haze of tenons white decayed tooth circles of rice huller sole Humiliation of couch 1 Mao in nice food far of winks hard for the s after lasting Qian to Pa Th e land of shelf slowly? -7 decibels, have certain reducing and shaking the result.

Reduce and shake and study and let the urban life be quieter