Objective Pinus tabuliformis, Betula platyphylla, Quercus mongolica, Larix principis-rupprechtii and Ulmus pumila are widely grown and planted in the North China. Their roots play an important role in anchoring soil and preventing landslides. Therefore, it is of scientific significance to study their root soil interface friction performance.
Method In this paper, the roots of five tree species dug from the Beigou Forest Farm of Mulan Forest Administration Bureau in Mulan Weichang County of Hebei Province, northern China were divided into several small sections according to different diameters, and the roots were buried in the soil specimen box with a dry density of 1.52 g/cm3 and a moisture content of 12.72%. The root pulling test machine developed by the plant mechanics laboratory of Beijing Forestry University was used to pull out the roots embedded in the soil, to explore the mechanism of root pulling out and analyze the factors affecting the friction force from different tree species and varied diameters.
Result (1) There were two failure modes in the process of root pulling out. When the maximum tensile strength of root was less than the maximum friction between root and soil, the root pulling off failure will occur, otherwise, the root pulling out failure will occur. (2) The maximum friction of root system increased as a power function with the diameter increasing and the fitting degree was very high. (3) The maximum shear stress of root soil interface of Q. mongolica and U. pumila decreased with the increase of diameter, while that of B. platyphylla, L. principis-rupprechtii and P. tabuliformis increased with the increase of diameter. (4) The shear stress and displacement curve of the root soil interface of five tree species can be fitted by the improved hyperbolic model, and the shear stress of each tree species reached the peak value when the displacement was 6% of the total value.
Conclusion The results show that different vegetation types and diameters have great influence on the soil consolidation effect of roots. The traditional prediction method of soil consolidation effect overestimates the soil consolidation effect of roots. Therefore, the influence of roots should be considered comprehensively in the construction of artificial protective forest.
Pinus tabuliformis, Betula platyphylla, Quercus mongolica, Larix principis-rupprechtii na Ulmus pumila hupandwa sana na kupandwa kaskazini mwa China. Mizizi yao huchangia sana kuimarisha udongo na kuzuia maporomoko ya ardhi. Kwa hiyo, ni ya umuhimu wa kisayansi kujifunza yao mizizi udongo interface msuguano utendaji. Katika utafiti wa kisasa, mizizi ya aina tano za miti iliyochimbwa kutoka Beigou Forest Farm ya Mulan Forest Administration Bureau katika Mulan Weichang County, Mkoa wa Hebei, China ya Kaskazini, iligawanywa katika sehemu kadhaa ndogo kulingana na kipenyo tofauti, na mizizi ilizikwa katika sanduku la sampuli ya udongo na wiani wa kavu wa 1.52 gcm3 na unyevu wa 12.72%. Mashine ya mtihani ya kuvuta mizizi iliyoundwa na maabara ya mitambo ya mimea ya Chuo Kikuu cha Misitu cha Beijing ilitumika kuvuta mizizi iliyoingizwa kwenye udongo, kuchunguza utaratibu wa kuvuta mizizi na kuchambua sababu zinazoathiri nguvu ya msuguano kutoka kwa spishi tofauti za miti na vipimo tofauti. Matokeo (1) Kulikuwa na njia mbili za kushindwa katika mchakato wa kuondoa mizizi. Wakati nguvu ya juu ya mvuto ya mizizi ilikuwa chini ya msuguano wa juu kati ya mizizi na udongo, kushindwa kwa kuvuta mizizi kutatokea, vinginevyo, kushindwa kwa kuvuta mizizi kutatokea. Kiwango cha juu cha msuguano wa mfumo wa mizizi iliongezeka kama kazi ya nguvu na kipenyo cha kuongezeka na kiwango cha kufaa kilikuwa cha juu sana. Kiwango cha juu cha msuguano wa shina la udongo wa Q. mongolica na U. pumila ulipungua na kuongezeka kwa kipenyo, wakati ule wa B. platyphylla, L. principes-rupprechtii na P. tabuliformis uliongezeka na kuongezeka kwa kipenyo. Mzunguko wa msukumo wa msukumo wa mizizi ya mimea mitano ya mti unaweza kuunganishwa na mfano wa hyperbolic ulioboreshwa, na msukumo wa msukumo wa kila mti wa mti ulifikia thamani ya kilele wakati msukumo ulikuwa 6% ya thamani ya jumla. Matokeo yanaonyesha kwamba aina tofauti za mimea na kipenyo vina ushawishi mkubwa juu ya athari ya kuimarisha udongo wa mizizi. Mbinu ya jadi ya utabiri wa athari ya kuimarisha udongo inazidi athari ya kuimarisha udongo wa mizizi. Kwa hiyo, ushawishi wa mizizi inapaswa kuzingatiwa kwa kina katika ujenzi wa msitu wa kinga bandia.