Measured Research On The Wind Driven Rain Erosion Of Hakka Earth Building Rammed Earth Wall

Fujian earth building has a long history, high artistic and scientific value. Afterthe success application for the list of world heritage, it’s more important to protect theearth building. This rammed earth wall as bearing structure of the building, there areusually more than1m wide wall thickness and more than1m wide cantilever eaves, ingeneral rainy season, large cantilever roof can protect the rammed earth wall are notaffected by rainfall erosion, but in the southeast coastal area often suffer fromtyphoon attacks, in the extreme weather, winds drive with heavy rainfall woulderosion the rammed earth wall, thus cause rammed earth wall structure damage, thispaper mainly studies the erosion measured of the rammed earth wall under the jointaction of wind and rain.This paper taking Fujian earth building as the research object, through the fieldmeasurement experimental method, mainly do the following aspects of contents:(1) Collect the local meteorological data, including wind speed, rainfall intensity,and carries on the statistics and analysis, respectively for wind speed, rainfallintensity probability distribution of the parameter estimation, and put forward thesuitable for their probability distribution function, which the wind speed probabilitydistribution model with extreme Ⅲ type fitting optimal,rainfall intensity probabilitydensity can be used extreme Ⅰ type and Weibull distribution fitting, andtheprobability distribution with Gamma and exponential distribution to fit the optimal.Joint distribution use the Gumbel copulas function to describe is the optimal, which isbased on extreme Ⅲ typeof wind speed distribution, Gamma distribution of rainfallintensity distribution.(2) Respective analysis the effectual characteristics of wind and rain, and basicoverview the characteristic parameters of raindrops. In the general calculation, thelevel of raindrop impact can be ignored. When extreme instantaneous rain strongmore than200mm/h extreme conditions, the rain impact on the structural can’t ignore.Rainfall for air density changes a little influence is negligible. (3) In the earth building local location, using the measurement of erosion stitchto measure the erosion damage of the rammed earth wall before and after the rainyseason. Through the analysis, it conclude that when rammed earth walls are completefor roof protection and in the general direction of the wind, rammed earth wallerosion depth relatively small; When rammed earth wall completely exposed no roofprotection and in the prevailing wind direction, rammed earth wall erosion depth isvery the largest, which is2-3times of the former.(4) Through artificial rainfall combined with wind tunnel test, to do the winddriven rain erosion experiments of rammed earth test samples. Study erosion damageunder the wind drive rain in different combination of wind and rain. The erosiondepth rammed earth test samples is increases with the increase of rainfall intensityand wind speed increases, but the increase of wind speed has a greater impact than theincrease of rainfall intensity to the erosion depth of rammed earth wall.